THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

LOS  ANGELES 


CONFIDENTIAL 

Registe,     N9     4090 


Issued  to . 


GUNNERY 
INSTRUCTIONS 

U.  S.  NAVY 

1913 


I 


WASHINGTON 
1918 


VD 

Navy  Department, 
Washington,  D.  C, 

September  29,  1913. 
The  following  Gunnery  Instructions,  U.  S.  Navy,  1913.  are 
approved  and  issued  to  the  service. 

This  volume  was  compiled  in  the  olhce  of  the  Director  of 
Target  Practice  and  Engineering  Competitions.  The  Gunnery 
Instructions,  1905,  forme,d  a  basis  of  compilation,  which  in- 
cluded a  revision  of  such  matter  from  the  1907  edition  of 
Ship  and  Gun  Drills  as  dealt  with  practical  naval  gunnery. 
In  the  preparation  of  this  manual  it  was  the  aim  to  seek 
assistance  from  as  many  officers  as  it  was  possible  and  prac- 
ticable to  reach;  many  officers  contributed  and  collaborated, 
and  reports  of  target  practice  were  freely  consulted.  Finally, 
the  manuscript  was  re,vised  by  the  1913  Board  on  Revision  of 
Ship  and  Gun  Drills,  1907. 

Particular  attention  is  called  to  article  713,  Naval  Instruc- 
tions, 1913.  regarding  the  care  to  be  exercised  with  this 
publication. 

.JosEPHUS  Daniels, 

Secretary  of  the  Navy. 
3 


963721 


CONTENTS. 


Articles.       Pages. 

Chapter  1. — Handling  men 1-21        7-11 

Chaptek  2. — General  principles  of  training.       22-30      12—14 
Chapter  3. — General     principles     of     naval 

gunnery   31-46      15-20 

Chapter  4. — Details  of   training,   individual 

guns    47-105       21-38 

Chapter  5. — Training  for  collective  gunfire. 

individual    ships 10&-144       39-48 

Chapter  6. — Training     for     collective     fire, 

several    ships 145-153      49-51 

Chapter  7. — Torpedo     defense 154-164      52-54 

Chapter  8. — Torpedo   training 165-209      55-75 

Chapter  9.— Hints  for  turret  officers 210-259      76-92 

Chapter  10. — Hints  for  officers  of  a  broad- 
side  battery 260-282    93-100 

Chapter  11. — Toi'pedo      vessels      and      sub- 
marines      283-297  101-105 

Chapter  12.— Notes  ou  target  practice 298-300  106-110 

Chapter  13. — Alignment  of  sights  and  bore 

sighting    301-326  111-129 

Chapter  14.— Fire-control    telephones 327-330  130-138 

Chapter  15.— Range   finders 337-342  139-143 

Chapter  16.— Spotting    343-410  144-177 

Chapter  17. — Problems   in   fire   control    and 

calibration    411-420  178-202 

Chapter  18.— Station    bills 421-427  203-209 

Chapter  19.— Errors   of    gunfire 428-478  210-247 

Chapter  20.— Rewards  and  scores 479-487  248-250 

Chapter  21. — Gun  pointers  and  turret  and 

gun    captains 488-509  251-260 

Index   261-281 

6 


CHAPTER  1. 
HANDLING  MEN. 

"  Biatoricalljf,  good  men  icith  poor  ships  are  better  than  poor  men 
with  good  ships." — Mahan. 

1.  Importance  of  proper  handling  of  men. — Of  far  greater 
importance  to  officers  than  any  material  or  tools  committed 
to  their  charge  is  the  personnel  with  which  they  are  con- 
cerned. The  spirit  and  training  of  the  men  has  always  been 
a  more  important  factor  in  winning  battles  than  the  charac- 
teristics of  the  ships  or  of  the  weapons  employed.  Success  in 
training  and  in  the  cultivation  of  this  spirit  depends  to  a  very 
considerable  degree  on  success  in  handling  men. 

2.  Self-training  on  the  part  of  officers. — It  is  not  fair  to 
the  ship  or  to  the  men  under  the  control  of  an  officer  to  make 
them  bear  the  brunt  of  personal  deficiencies  existing  because 
of  a  neglect  of  self-training,  which  is  incumbent  on  all  officers. 
If  satisfactory  results  in  handling  a  command  do  not  appear 
to  be  forthcoming,  an  officer  should  make  a  study  of  himself, 
his  methods,  bearing,  and  attitude.  The  cause  of  the  difficulty 
may  be  discovered. 

3.  Force  of  example. — Men  will  take  just  as  much  interest 
in  their  duties  and  work  just  as  hard  as  the  officers  who  are 
placed  over  them.  Example  appeals  strongly  to  men,  and 
officers  must  bear  in  mind  that  their  bearing,  manner,  and 
language  in  dealing  with  seniors,  as  well  as  juniors,  are  all 
copied  by  their  subordinates.  An  officer  must  at  all  times 
set  an  example  of  industry,  zeal,  initiative,  and  punctuality, 
as  well  as  neatness  of  dress  and  correctness  of  bearing,  if  he 
is  to  expect  these  from  his  men. 

'        f  . 


8  GUNNERY  INSTRUCTIONS. 

4.  Criticism  of  superiors. — Hostile  criticism  of  authority 
will  ruin  any  organization  and  completely  destroy  unity  of 
action.  A  subordinate  is  seldom  in  a  position  to  judge  of  tlie 
actions  of  his  superiors  intelligently  and  should  not  be  prone 
to  criticize  until  aware  of  all  circumstances  and  facts.  De- 
structive criticism  whicli  is  born  in  officers'  messes  is  con- 
tagious, and  will  soon  spread  through  the  ship  and  completely 
kill  sliip  spirit  Cooperation  is  essential  on  the  part  of  all 
hands.  Each  individual  must  be  assured  that  his  own  part 
and  task  are  thoroughly  accomplished  and  in  a  way  which 
will  best  assist  others  working  toward  the  same  end  and 
while  yielding  unqualified  support  to  authority.  This  is  es- 
sential to  success  in  any  organzation,  where  many  men  are 
employed,  as  a  fundamental  of  discipline. 

5.  First  attributes  of  an  officer. — Good  manners,  coolness, 
and  self-control  are  the  first  attributes  of  an  officer  and  are 
just  as  important  in  dealing  with  juniors  as  w'ith  seniors. 
Leadership  is  an  essential.  It  is  fundamentally  based  on 
proved  superiority.  The  officer  must  be  first  in  everything  at 
all  times. 

6.  Importance  of  understanding  individuals. — A  most  im- 
portant thing  is  to  know  men  thoroughly,  their  peculiarities, 
abilities,  weaknesses,  character,  etc. 

7.  Methods  of  handling  men. — Praise  will  frequently  better 
promote  interest  and  efficiency  than  censure  or  punishment. 
Be  strict,  but  not  harsh.  Remember  that  you  are  dealing 
with  individuals  as  sensitive  and  jealous  of  their  rights  as 
yourself.  Fairness  and  impartiality  in  dealing  with  them  are 
essentials.  But  little  good  and  often  gi-eat  evil  is  accomplished 
by  unnecessary  shouting.  Nothing  is  more  discouraging  to 
an  individual  than  the  finding  of  fault  with  him  when  he  Is 
using  his  best  endeavors. 

8.  Impoilance  of  interesting  men  in  work. — No  one  objects 
to  useful  work.  Interest  your  men  in  what  they  are  doing. 
Be  sure  that  they  understand  what  it  is  intended  to  accom- 


GUNNERY  INSTRUCTIONS.  9 

pllsli  and  why.  At  drill,  when  teaching  certain  details,  ex- 
plain why  these  details  are  necessary.  Point  out  the  diffi- 
culties and  the  methods  for  overcoming  them, 

9.  Suggestions  from  crew. — Never  disregard,  but  welcome, 
the  suggestions  from  your  petty  officers  and  men.  Give  all 
consideration,  and  if  suggestions  are  not  practicable  explain 
v,hy.  Such  an  attitude  on  the  part  of  an  officer  will  always 
lielp  to  promote  and  encourage  a  live  and  personal  interest 
ii.  tlieir  work  on  tlie  part  of  the  crew,  and  frequently  many 
helpful  ideas  will  be  offered. 

10.  Seizing  opportunities. — Take  full  advantage  of  opportu- 
nities as  they  are  presented.  There  is  too  much  to  be  done 
to  expect  unlimited  time  to  attend  to  all  the  details  of  train- 
ing and  developn^ent  separately.  The  best  organization  is  not 
one  in  which  a  single  individual  directs  all  details.  It  must 
be  such  that  sul)ordinate  leaders  are  given  specific  tasks  for 
llie  accomplishment  of  which  they  are  given  the  necessary  au- 
thority and  for  which  they  are  held  rigidly  responsible.  The 
leader  must  organize  his  forces  and  arrange  his  program  ac- 
cordingly, taking  full  advantage  of  every  opportunity  that 
occurs.  Many  of  the  complaints  regarding  lack  of  opportunity 
come  from  those  who  fail  to  recognize  opportunities  as  they 
occur  and  do  not  fully  avail  themselves  thereof.  Facilities, 
conveniences,  and  opportunities  are  seldom  the  best,  but  be 
sure  to  make  the  most  of  such  as  are  presented. 

11.  Petty  oflacers, — Petty  officers  are  indispensable  assist- 
ants. They  must  be  able  to  realize  and  to  exercise  their  re- 
sponsibilities. Expect  the  same  loyal  support  from  them  that 
you  afford  your  superiors.  Endeavor  to  handle  the  junior 
ratings  of  your  division  through  their  own  petty  officers,  and 
train  your  junior  ratings  to  obtain  information  and  instruc- 
tion from  ther  own  petty  officers. 

12.  Smartness  and  cleanliness  essential. — A  division  that 
1::  smart  in  infantry,  boat,  and  other  drills  is  more  apt  to  be 
smart  in  gunnery  than  one  that  is  generally  slack.    Cleanll- 


10  GUNNERY  INSTETJCTIONS. 

ness  of  uniform,  person,  and  of  ship  are  all  important.     No 
one  is  proud  of  a  dirty  ship  or  a  dirty  shipmate. 

13.  Competition. — Stimulate  competition  by  all  legitimate 
means.  Arouse  a  desire  to  beat  the  other  fellow,  but  only  by 
Jionest  and  fair  means.  Analyze  and  post  all  records  and 
scores. 

14.  At  quarters  and  drills. — At  quarters  set  an  example 
yourself  in  military  form  and  manners  and  your  division  will 
imitate  you.  Do  not  hold  men  at  "attention"  longer  than 
necessary ;  but  when  the  command  is  "attention,"  enforce  it. 

15.  Inspections. — At  daily  inspection  at  quarters  avoid 
arguing  with  or  questioning  the  men  while  in  ranks  as  to 
delinquencies  in  uniform.  Make  a  mental  note  of  each  case 
and  overhaul  the  man  about  it  after  quarters.  The  best  form 
is  to  inspect  your  division  without  allowing  yourself  directly 
to  address  a  man  in  ranks  about  deficiencies  in  his  personal 
appearance.  To  call  a  man  down  in  the  presence  of  others 
about  his  personal  appearance  does  not  nourish  his  self- 
respect,  which  if  destroyed  ends  his  usefulness. 

16.  Particular  care  with,  young  men. — Many  young  men 
are  discharged  as  undesirable  or  with  bad-conduct  discharges 
who  might  have  been  saved  to  the  Navy  had  they  had  more 
official  interest  and  encouragement  bestowed  on  them  by  the 
division  officer.  Youngsters  who  are  inclined  to  be  shiftless 
require  forethought  on  the  division  officer's  part  to  keep  them 
from  delinquencies.  The  more  a  young  man  is  inclined  to  be 
delinquent  in  petty  matters  the  more  often  a  cheering  en- 
couragement will  bear  fruit.  When  a  man  is  bracing  up, 
commend  him. 

17.  Commendation,  censure,  and  reports. — Commendations 
might  well  be  heard  by  others  and  when  merited  should  be 
prompt.  Censure  should  not  be  public.  Reports  of  a  trifling 
nature  are  undesirable.  Never  report  a  man  unless  there  is 
ample  and  good  reason  for  believing  that  he  has  intentionally 
committed  an  offense  deserving  of  punishment. 


GUNNERY  INSTRUCTIONS.  11 

18.  Giving  commands. — Much  depends  on  the  manner  in 
which  a  command  is  given.  The  voice  and  tone  employed  and 
method  of  expression  are  of  importance,  as  well  as  the  char- 
acter of  the  command.  All  uncertainty  is  to  be  avoided,  and 
the  manner  should  carry  with  it  the  impression  that  obedience 
is  expected.  Clearness  to  the  person  to  whom  the  command  is 
given  is  essential.  No  command  should  be  given  unless  it 
can  be  obeyed,  and  when  given  it  must  be  obeyed.  The  giving 
of  unnecessary  commands  should  be  avoideil. 

19.  Comforts  of  men. — Carefully  look  out  for  the  comforts 
of  the  men.  The  successful  ship  is  the  happy  ship,  and  the 
men  must  feel  that  their  ship  is  their  home.  The  Navy  owes 
every  man  reasonable  comfort  in  a  place  to  sit,  to  eat,  and  a 
billet  that  will  afford  a  night's  rest.  Look  out  for  these. 
Details,  often  trifling,  in  controlling  the  uniform,  berthing, 
messing,  and  living  arrangements  may  greatly  contribute  to 
their  welfare  and  contentment.  It  is  an  essential  part  of  an 
officer's  duty  to  care  for  such  details.  On  Saturday,  Sunday, 
and  holidays,  and  after  working  hours,  initiate  recreation 
for  your  division,  such  as  sailing  parties,  swimming  parties, 
and  the  like. 

20.  Avoidance  of  petty  annoyances. — Guard  your  people 
from  petty  annoyances,  such  as  interference  with  meal  hours. 
If  any  are  away  at  meal  time,  be  sure  they  are  provided  for 
on  their  return.  AVhen  men  have  been  exposed  to  bad  weather 
or  have  had  unusually  hard  work,  as  is  not  uncommonly  neces- 
sary on  board  ship,  be  sure  that  their  well-being  is  looked 
out  for. 

21.  Importance  of  minor  details. — These  small  matters 
have  a  great  influence.  Once  the  men  of  a  ship  realize  that 
the  officers  have  their  interest  at  heart  the  success  of  the  ship 
is  assured.  In  no  other  way  can  a  strong  ship  spirit  be  de- 
veloped, and  a  slight  effort  in  this  direction  on  the  part  of 
officers  will  accomplish  great  results. 


CHAPTER  2. 
GENERAL  PRINCIPLES  OF  TRAINING. 

22.  Training  for  war,  the  first  principle. — The  first  prin- 
ciple to  remember  in  training  is  that  war  should  be  con- 
sidered a  contingency  that  is  liliely  to  occur  with  but  little 
warning.  A  second  is  that  the  closer  the  training  exercises  in 
time  of  peace  resemble  the  conditions  to  be  expected  in  battle, 
the  fewer  will  be  the  derangements  and  the  less  will  become 
the  influence  of  danger  and  of  these  derangements  on  the 
moral  qualities  of  the  crew. 

23.  Training-  more  important  than  material. — Unless  the 
naval  officer,  in  time  of  peace,  devotes  thought  and  study  to 
the  important  feature  of  his  profession — making  the  most  out 
of  his  command,  whatever  it  may  be — he  can  not  prepare  him- 
self for  the  duties  that  will  come  to  him  in  war.  In  times  of 
peace  it  is  natural  for  other  matters,  such  as  features  of 
administration,  material,  and  design  to  occupy  first  place  in 
the  minds  of  those  who  will  be  called  upon  in  war  to  use 
weapons  and  ships.  Preparations  for  war  can  not  be  ade- 
quately accomplished  after  hostilities  have  begun,  and  unless 
the  training  has  been  correct  and  sufficient  the  officer  will, 
when  called  upon  for  a  demonstration  of  his  proficiency,  find 
himself  in  the  position  of  the  indifferent  workman  who  in- 
variably complains  most  bitterly  of  his  tools.  Sticcess  tvill 
depend  to  a  far  greater  degree  on  the  spirit  and  morale  of  the 
personnel,  and  on  the  training  and  ability  of  all  to  eoordinate 
their  efforts,  than  on  any  features  of  administration  or  mate- 
rial.   The  proper  bearing  and  zealous  efforts  of  every  ofiicer 

12 


GITNNERY  INSTRUCTIONS.  18 

are  directly  reflected  in  the  Interest  and  enthusiasm  with 
which  the  crew  carries  on  the  liard  work  necessary  on  their 
part.  The  importance  of  retaining  the  interest  of  the  men  is 
sometimes  not  fully  appreciated.  The  successful  and  happy 
ship  is  the  one  in  which  the  men  are  encouraged  to  have  a 
knowledge,  interest,  and  pride  in  their  work.  These  can  only 
be  aroused  by  intelligent  and  cheerful  zeal  on  the  part  of  all 
officers. 

24.  Character  of  system. — The  system  of  training  herein 
prescribed  begins  with  the  selection  of  the  units  of  the  gun 
crews  and  describes  the  training  necessary  to  render  each 
expert  in  his  individual  duties.  The  gun  crew  is  then  per- 
fected as  a  team,  and  when  this  is  accomplished  the  training 
is  for  the  development  of  the  ship's  battery  as  a  whole,  and 
finally  for  the  collective  fire  of  the  batteries  of  more  than 
one  ship. 

25.  Utilization  of  the  spirit  of  competition. — This  require- 
ment is  fundamental.  The  natural  desire  of  one  man  to  excel 
another  in  any  test  of  skill  is  an  incentive  to  thorough  train- 
ing that  may  be  regarded  as  the  basis  of  all  real  success. 
However  complete  may  be  the  .system  or  the  apparatus,  or 
however  diligent  and  faithful  the  officer,  unless  the  desire  to 
excel  is  excited  the  result  will  be  mediocre.  Perfunctory 
training  will  never  produce  as  good  an  oarsman  as  boat  rac- 
ing. This  spirit  should  be  fostered  and  utilized  in  the  daily 
drills  by  pitting  individuals  and  crews  against  one  another. 
t!are  should  be  taken  to  avoid  all  questionable  or  unfair 
methods. 

26.  Final  purpose  of  training. — The  final  purpose  of  com- 
petitive training,  battle  efficiency,  must  not  be  lost  sight  of. 
The  competition  is  but  the  means  to  that  end.  What  is  de- 
sired is  a  state  of  efficiency  or  a  condition  which  will  enable 
a  vessel  to  make  a  good  score  under  any  circumstances  and 
not  only  under  the  peculiar  conditions  of  a  particular 
problem. 


14  GUNNEEY  INSTRTJCTIONS. 

27.  Permanence  in  stations. — The  skill  of  the  ship  in  gun- 
nery depends  directly  upon  the  skill  of  each  officer  and  man 
ill  his  individual  duties.  Neither  officers  nor  men  can  reach 
their  maximum  skill  if  they  are  frequently  shifted  from  one 
station  to  another.  Members  of  crews  should,  however,  be 
exercised  in  stations  other  than  those  they  habitually  fill,  in 
order  that  casualties  lo  personnel  shall  not  silence  the  fire. 

28.  Casualties. — Any  training  that  does  not  pi*epare  for  and 
fully  anticipate  casualties  to  both  personnel  and  materiel  is 
incomplete.  It  should  be  remembered  that  in  preparing  for 
casualties  no  methods  or  devices  should  be  allowed  that  would 
not  be  practicable  in  action.  Many  casualties  probable  in 
battle  can  not  be  ordered  at  the  times  of  target  practice  with- 
out introducing  an  element  of  danger  or  interfering  with  com- 
petitions.   These  must  be  prepared  for  at  other  times. 

29.  Service  conditions  on  drill. — In  conducting  drill  the 
regular  battle  system  of  communications  should  always  be 
employed.  Turrets  should  be  closed  as  would  be  the  case  in 
service.  The  conditions  during  drill  should  be  made  harder 
than  they  would  be  at  target  practice  and,  if  possible,  as  dif- 
ficult as  would  be  the  case  in  action.  Then  when  unforeseen 
contingencies  arise  men  and  officers  will  be  schooled  in  steadi- 
ness. Though  dummy  charges  are  used,  the  safety  orders 
must  be  carefully  observed.  A  carelessness  on  the  part  of 
officers,  begotten  by  either  ignorance  or  failure  to  appreciate 
their  duties  is  immediately  copied  by  the  men. 

30.  Investigation  of  unsatisfactory  performances. — An  un-* 
satisfactory  performance  at  drill  should  always  be  carefully 
investigated  and  the  cause  definitely  determined  and  removed. 


CHAPTER  3. 
GENERAL  PRINCIPLES  OF  NAVAL  GUNNERY. 

31.  Final  objective. — The  final  objective  of  all  naval  gun- 
nery training  is  the  development  of  an  ability  to  hit  an  enemy 
rapidly,  at  varying  ranges,  and  under  different  conditions  of 
sea,  weather,  and  light.  The  subject  is  a  broad  and  compre- 
hensive one.  In  its  final  stage  the  training  becomes  that  of 
the  fleet,  and  involves  the  development  of  units  to  the  highest 
efficiency. 

32.  Final  stage  of  training'. — The  gunnery  training  in  this 
final  stage  becomes  closely  me^-ged  with  tactical  development, 
as  it  is  not  suflicient  to  have  good  weapons  and  to  be  able  to 
use  them  at  target  practice,  they  must  all  be  brought  into 
action  and  maintained  there  properly.  Unless  a  maximum  of 
effective  fire  delivery  with  both  guns  and  torpedoes  is  main- 
tained from  each  vessel  of  a  force  engaged  in  battle,  the  gun- 
nery training  can  not  be  said  to  have  been  complete.  The 
different  classes  of  ships  must  be  so  trained  that  they  may 
all  effectively  operate  together. 

PROFICIENCY  WITH  GUNS.     (Fired  individually). 

33.  First  essential. — It  is  imperative  that  each  ship  be  able 
to  hit,  with  rapidity,  a  target  under  favorable  conditions. 
To  make  this  possible,  when  all  guns  are  firing,  it  is  necessary 
that  the  vessel  be  able  to  do  so  first  with  each  individual  gun 
firing  singly, 

15 


16  GUNNEEY  INSTRUCTIONS. 

34.  Analysis  of  principles. — An  analysis  of  the  principles 
of  naval  gunnery  must  therefore  first  reduce  itself  to  an 
analysis  of  the  principles  involved  in  excellence,  with  the 
individual  gun. 

35.  Excellence,  how  measured. — Excellence  in  gunfire  is 
measured  by  rapidity  of  hitting.  It  is  evident  that  however 
large  a  percentage  of  hits  a  gun  may  make,  if  these  hits  are 
not  made  with  the  greatest  possible  rapidity,  the  gun  will 
have  failed  to  attain  its  highest  efficiency.  Rapidity  of  fire 
with  inaccurate  pointing  is  useless  and  demoralizing,  and  en- 
tirely prevents  control  of  the  fire  of  the  gun  whe^n  fired  indi- 
Aidually,  and  makes  impossible  the  successful  control  of  a 
group  of  guns  when  fired  collectively.  The  following  may  be 
regarded  as  the  two  essential  elements  of  excellence  in  gun- 
fire: (A)  Accuracy  of  fire;  (B)  Rapidity  of  fire. 

36.  (A)  Accuracy  of  fire. — This  depends  upon : 

I.  The  accuracy  of  pointing. 

II.  Satisfactory  sight  setting. 

III.  Elimination  or  reduction  of  errors  of  gunfire  as  men- 
tioned in  chapter  19. 

37.  I.   The  accuracy  of  pointing  depends  upon: 

1.  The  skill  of  the  individual  pointer,  which  is  developed 
by— 

(a)  Continued  practice  at  his  own  gun  or  type  of  gun  with 
mechanical  tai'gets,  in  port  or  at  sea,  when  other  methods  are 
not  available. 

(6)  Using  a  check  telescope  at  sea. 

(c)  Firing  with  subcaliber. 

(d)  Actual  firing  at  target  practice. 

2.  The  condition  in  which  the  sight,  the  gun,  the  mount, 
and  the  various  appurtenances  which  affect  accurate  shoot- 
ing are  kept,  together  with  the  degree  of  excellence  in  their 
design  and  manufacture.  Unless  tiie  design  is  sal  isf actory,  and 
unles^the  gun,  mount,  sights,  and  accessories  are  maintained 
in  such  condition  that  the  difficulties  in  aiming  and  firing  are 


GUNNERY  INSTETTCTIONS.  V 

minimized,  the  accuracy  of  pointing  will  be  affected.  This  ap- 
plies to  the  facility  of  operation,  and  to  the  proper  functioning 
of  each  individual  part.  A  neglected  mount  renders  pointing 
difficult  and  hence  conduces  to  inaccuracy.  Neglected  sights 
always  invite  failure.  If  they  are  out  of  adjustment  they 
insure  great  dispersion  and  misses.  If  they  are  weak  and 
liable  to  derangement,  they  may  jar  out  of  adjustment  while 
firing  is  taking  place  and  thus  invite  disaster.  Neglected  fir- 
ing connections,  locks,  etc.,  promote  hangfires,  misfires,  or  pro- 
long firing  intervals,  all  of  which  militate  against  good  point- 
ing and  are  serious  hindrances  to  rapidity  of  hitting. 
38.  II.  Satisfactory  sig'ht  setting  depends  upon: 
(«)  The  adjustment  of  the  sight.  The  sight  must  travel 
with  the  gun  at  all  angles  of  elevation.  Lost  motion  is  al- 
most sure  to  appear  in  time  in  the  older  types  of  sights,  and 
careful  supervision  and  frequent  checking  up  of  the  adjust- 
ment thereof  are  essential.    (See  chap.  13  on  boresighting.) 

(b)  The  accuracy  and  precision  of  the  orders  given  to  the 
sight  setter  concerning  the  setting  of  sights.  This  depends 
upon  (1)  the  accuracy  with  which  the  sight-bar  range  has 
been  determined,  which  may  be  regarded  as  the  most  difficult 
problem  in  naval  gunnery;  (2)  the  arrangement  and  condition 
of  the  .system  of  communications,  together  with  the  skill  with 
which  it  is  used. 

(c)  The  promptness  and  precision  with  which  these  orders 
are  obeyed.  It  is  manifest  that  however  perfect  the  gun,  the 
mount,  the  crew,  and  the  ammunition,  unless  the  sights  are 
correctly  set,  the  projectile  will  certainly  miss  the  target. 
Creat  care  must  be  exercised  in  the  selection  and  training  of 
sight  setters,  and  the  accuracy  with  which  the  setting  of  the 
sights  is  accomplished  should  be  carefully  checked  up  after, 
and.  if  possible,  during  each  run  at  target  practice. 

Whatever  the  form  of  firing,  the  sight  setter's  duty  remains 
the  same.    It  is  to  set  the  sight  as  accurately  and  as  quickly 
34776—18 2 


18  GUNNERY  INSTEITCTIONS. 

as  possible,  both  laterally  and  in  elevation,  each  time  a  new 
deflection  or  range  is  ordered.  The  pointer  always  aims  at 
exactly  the  same  place,  and  all  errors  are  corrected  by  alter- 
ing the  sights. 

39.  III.  Elimination  or  reduction  of  errors  of  gunfire. — 
These  eri-ors  are  discussed  at  length  in  chapter  19. 

40.  Uniformity  of  loading. — Precision  of  fire  depends  to  a 
considerable  degi'ee  on  the  uniformity  with  which  the  opera- 
tions of  loading  are  completed.  In  B.  L.  R.  guns  the  shell 
must  invariably  be  seated,  the  ignition  ends  of  sections  of  the 
charge  must  be  to  the  rear,  and  the  Ignition  end  of  the  last 
section  of  the  charge  must  be  close  to  the  mushroom  face, 

41.  Necessity  for  elimination  of  errors. — It  is  manifest 
that  as  the  ranges  increase,  and  the  danger  spaces  are  dimin- 
ished, the  necessity  for  reducing  and,  if  possible,  eliminating 
anything  which  may  produce  errors  in  the  accuracy  of  gun- 
fire should  be  carefully  investigated.  To  a  considerable  de- 
gree investigations  along  these  lines  are  possible  only  at 
proving  grounds,  but  officers  afloat  should  carefully  study  all 
data  which  may  have  a  bearing  on  these  errors.  Such  data 
may  be  obtained  from  the  Range  Tables,  and  other  ordnance 
pamphlets  and  works  on  ballistics.  As  these  errors  are  re- 
duced, the  possibilities  of  increasing  the  effective  range  are 
vastly  increased. 

42.  (B)  Rapidity  of  fire. — This  depends  upon : 
/.  The  rapidity  of  loading. 

II.  The  promptness  with  which  the  pointer  fires  after  the 
gun  is  ready,  or  the  firing  signal  has  been  given;  or,  briefly, 
rapidity  of  pointing, 

///.  The  facility  with  ichich  fire  may  be  controlled. 

43.  I,  Rapidity  of  loading  with  modern  guns  depends  upon : 

(a)  The  rapidity  with  which  each  member  of  the  gun  crew 
performs  his  duty. 

( b )  The  precision  with  which  each  one  performs  his  allotted 
portion  of  the  drill. 


GUNNERY  INSTRUCTIONS.  10 

(c)  The  "team  work;"  that  is,  on  each  member  of  the  ^n 
crew  performing  his  duty  at  exactly  tlie  proper  time  and  in 
exactly  the  proper  sequence,  and  the  elimination  of  interfer- 
ences between  individuals  of  the  crew. 

Accuracy  and  thoroughness  in  every  detail  are  requisites  to 
rapidity  of  loading.  Eagerness  for  excessive  rapidity  may 
result  in  interference,  confusion,  and  casualties  that  can  be 
avoided  only  by  precision  in  every  movement.  Certain  of 
these  delays,  such  as  the  raising  of  a  burr,  the  jamming  of  a 
cartridge  case,  or  the  breaking  of  a  powder  bag  may  more 
seriously  interfere  with  the  rapidity  of  fire  than  the  delibera- 
tion necessary  to  surely  avoid  them. 

44.  II.  Rapidity  of  pointing,  like  accuracy  of  pointing,  de- 
pends upon : 

(a)  The  skill  of  the  pointer. 

(b)  The  condition  of  the  material. 

A  skillful  pointer  will,  under  ordinary  conditions,  keep  a 
gun  of  intermediate  or  secondary  caliber,  on  a  modern  gun 
mount  installed  in  a  vessel  that  is  a  good  gun  platform, 
practically  continuously  pointed  at  the  target,  provided  the 
mount  is  maintained  in  a  perfect  condition.  The  gun  is  there- 
fore aimed  and  prepared  to  fire  shortly  after  the  instant  the 
pointer  is  notified  that  the  gun  is  "  ready."  If  to  this  degree 
of  skill  of  the  pointer  and  excellence  of  mount  is  added  a 
firing  mechanism  in  such  efficient  condition  that  the  gun  will 
fire  when  the  pointer  presses  the  firing  key,  ignoring  for  the 
moment  questions  of  fire  control,  the  rapidity  of  aimed  shots 
is  made  practically  equal  to  the  rapidity  with  which  unaimed 
shots  may  be  fired.  So  long  as  this  degree  of  rapidity  is 
possible  with  any  gim,  it  is  evident  that  any  time  which 
elapses  between  the  word  "  ready  "  and  the  firing  of  the  gun, 
when  not  firing  on  order  or  on  salvo  signals,  is  a  loss.  A 
lack  of  adequate  rapidity  of  pointing  may  result  in  a  failure 
to  fire  when  the  signal  is  given,  which  lessens  materially  the 


20  GUNNEEY  INSTRUCTIONS. 

fire  delivery  of  the  ship,  on  the  efficiency  of  which  depends 
the  value  of  the  vessel  as  a  battle  unit.  It  must  be  remem- 
bered that  rapidity  of  pointing  is  never  to  be  obtained  by  the 
sacrifice  of  accuracy. 

45.  III.  Facility  of  fire  control. — At  sliort,  measured 
ranges,  when  firing  guns  singly,  the  spotting  of  shots  other 
than  the  first  shot  in  a  string  should  be  unnecessary.  At  long 
ranges  the  delays  incident  to  spotting  are  of  greater  moment, 
as  the  time  of  flight  and  intervals  of  time  necessary  for  the 
spotter  to  decide  on  his  correction  and  to  have  this  correction 
appear  on  the  sights,  are  all  appreciable.  Effort  should  be 
constant  to  lessen  these  delays. 

The  above  remarks  refer  to  day  firing.  They  apply,  how- 
ever, equally  well  at  night.  Gunnery  at  night  is  further  com- 
plicated by — 

(a)  The  necessity  for  illuminating  the  target. 

(6)  The  difficulties  of  properly  controlling  searchlights. 

(c)  The  annoyances  incident  to  blast  of  guns  and  glare  of 
lights,  which  are  increased  by  the  gases  of  discharge. 

(d)  The  difficulties  incident  to  setting  sights  with  artificial 
illumination  and  of  worliing  about  the  guns  under  unfavorable 
conditions  of  illumination. 

46.  Necessity  for  cooperation. — From  the  above  it  is  ap- 
parent that  skill  in  gunnery  depends  not  upon  the  pointer 
alone,  but  upon  every  person  participating  in  the  practice — 
on  the  ship-control,  fire-conti'ol,  and  searchlight-control  parties, 
the  division  officer,  the  gun  captain,  pointers,  the  sight  setter, 
and  on  each  individual  member  of  the  gun  crew.  The  great- 
est rapidity  of  hitting  can  be  attained  only  by  the  united 
efforts  of  each  person  concerned,  working  in  complete  har- 
mony with  every  other  member  of  the  crew.  A  failure  in  the 
slightest  detail,  on  the  part  of  any  one  participant,  may  ma- 
terially reduce  the  rapidity  of  hitting,  and  thus  nullify  the 
greatest  possible  excellence  on  the  part  of  others. 


CHAPTER  4. 
DETAILS  OF  TRAINING— INDIVIDUAL  GUNS. 

47.  Ordnance  pamphlets. — Attention  is  invited  to  the  nu- 
luerous  pamphlets  published  by  the  Bureau  of  Ordnance  con- 
tuinirifr  descriptions  of  material  and  methods  of  operation. 

48.  Ordnance  Instructions. — Particular  attention  is  called 
to  Chapter  26,  Ordnance  Instructions,  Navy  Regulations,  and 
Naval  Instructions,  1913.  These  instructions  must  be  under- 
stood by  all  officers  in  any  way  concerned  with  the  ordnance 

outfit. 

49.  Selection  of  crew. — There  are  now  sufficient  trained 
men  in  the  service  so  that  it  should  be  very  seldom  that  a 
gun's  crew  has  to  be  selected  entirely  from  new  hands.  With 
men  who  have  been  in  the  service  for  some  time  their  pre- 
vious experiences,  service,  gunnery,  and  torpedo  records 
should  be  considered  when  assigning  them  to  battle  stations. 

50.  Stationing  the  gun  crew. — The  division  oflicer  should 
first  select  the  gun  captain  and  members  of  the  gun-pointer 
group  and  then  the  others  of  the  crew%  taking  into  considera- 
tion mental  and  physical  qualifications  and  the  requirements 
of  the  respective  stations.  This  first  assignment  is,  of  course, 
tentative  and  subject  to  change  when  qualifications  are  better 
known.  Attention  is  invited  to  article  2501  (2)  (3),  Naval 
Instructions,  regarding  the  selection  of  gun  pointers  and  the 
stationing  of  gun  captains  and  pointers. 

51.  Selection  of  gun  captain. — The  general  requirements 
for  a  qualified  gun  captain  are  thorough  practical  knowledge 
of  the  gun,  mount,  and  various  appurtenances,  also  of  the 

21 


22  OTJUNERir  INSTEUCTIOFS. 

drill  giin,  and  a  sj'stem  of  training,  together  with  the  execu- 
tive ability  to  drill  and  command  the  crew.  He  should  be  a 
man  of  resource  and  quick  action,  for  in  battle  he  may  be 
called  upon  to  act  upon  his  own  responsibility.  The  man's 
executive  ability  and  general  intelligence  should  be  given  the 
greatest  weight,  as  these,  combined  with  zeal,  will  quickly 
develop  the  necessary  knowledge.  As  a  rule,  petty  officers, 
being  initially  a  class  selected  for  these  qualities,  will  be  the 
men  best  fitted  for  these  positions.  A  seaman  who  is  qualified 
for  gun  captain  generally  possesses  the  qualifications  that 
entitle  him  to  promotion  to  petty  officer,  third  class. 

52.  Selection  of  gun  pointers. — Men  with  the  proper  quali- 
fications may  be  trained  as  gun  pointers  quickly  and  easily. 
In  selecting  gun  pointers,  division  officers  should  give  weight 
to  the  man's  ability  to  shoot  straight,  as  indicated  by  his 
record  with  small  arms,  in  connection  with  good  eyesight, 
nerve,  and  a  cool,  nonexcitable  disposition.  The  importance 
of  these  latte;-  qualities  may  not  appear  in  preliminary  train- 
ing, but  they  are  essential  and  should  receive  first  considera- 
tion. Men  whose  nerve  and  physical  training  will  withstand 
the  exhaustive  tests  incident  to  battle  are  those  to  be  desired. 
A  man's  rating,  general  knowledge,  or  executive  ability  should 
not  be  allowed  to  have  weight  in  his  selection  as  a  gun  pointer. 

53.  Selection  of  sight  setter. — The  requirement  that  the 
sight  setter  receive  regular  training  and  act  as  second  pointer 
for  turret  guns  necessitates  that  the  same  care  be  exercised 
ill  the  selection  of  candidates  for  this  position  as  for  pointers. 

54.  Expiration  of  enlistment. — An  important  point  to  be 
considered  in  connection  with  the  selection  of  gun  pointers  is 
the  expiration  of  the  candidate's  enlistment.  A  man  who  has 
already  qualified  as  gun  pointer  will  not  be  deprived  of  his 
position  at  the  gun  (and  hence  of  his  extra  pay)  on  this  ac- 
count alone,  but,  when  practicable,  no  new  man  should  be 
selected  for  training  if  the  expiration  of  his  enlistment  will 
not  permit  him  to  serve  as  a  gun  pointer  for  at  least  one  year 


GUNNERY  INSTEUCTIONS.  23 

after  qualifying  for  that  position.  The  longer  a  man  has  to 
serve,  the  greater  his  desirability  as  a  pointer,  other  consid- 
erations being  equal.  After  a  practice  each  division  officer 
should  ascertain  how  many  of  his  pointers  will  remain  until 
the  next  practice,  and  immediately  put  men  in  ti-aining  to 
replace  those  who  will  not  be  aboard.  In  several  instances 
ships  have  been  called  upon  to  hold  practice  very  shortly  after 
commissioning,  and  have  demonstrated  that  where  intelligent 
effort  was  made  in  stationing  and  exercising  crews  creditable 
performances  were  quickly  possible. 

55.  Spare  set  of  pointers. — A  spare  set  of  pointers  and 
sight  setters  will  be  kept  in  training  for  each  gun  at  all  times. 

56.  Bunching  of  shot. — The  value  of  a  pointer  should  be 
judged  by, the  way  he  bunches  his  shots.  A  man  may  show 
aptitude  by  bunching,  while  another  may  demonstrate  by 
scattering  his  shots  that  he  has  not  profited  by  training  and 
is  undesirable  as  a  pointer.  In  forming  his  judgment  the 
division  office^  should  be  sure  that  the  scattering  of  shots  has 
not  been  due  to  inaccurate  sight  setting  or  to  other  causes. 

57.  Training  pointer. — The  training  pointer  occupies  a  most 
responsible  and  difficult  position,  and  particular  attention 
should  be  given  to  the  development  of  men  for  this  station. 

58.  Devices  for  training. — The  following  mechanical  de- 
vices are  used  for  training  members  of  gun  crews.  Success 
attained  with  them  depends  to  a  considerable  degree  upon  the 
accuracy  with  which  the  apparatus  is  installed: 

(1)  The  dotter. 

(2)  The  Morris  tube. 

(3)  The  check  telescoiie. 

(4)  Subcaliber  attachments. 

(5)  The  loading  machine. 

Having  developed  skill  individually,  the  following  develops 
the  skill  of  the  crew  as  a  whole: 

(6)  Drill  at  gun. 

(7)  Target  practice. 


24  aUUirEEY  INSTEUCTI0N3. 

The  individual  function  of  tliese  will  be  explained  in  the 
oi'der  mentioned.  This  explanation  is  made  in  considerable 
detail  for  the  benefit  of  inexperienced  officers. 

59.  Features  taught  by  training  with  mechanical  tar- 
gets.— The  following  features  of  training  gun-pointer  groups 
are  particularly  developed  with  mechanical  appliances : 

(a)  Position  of  pointer  at  the  gun. — Unless  the  pointer 
assumes  an  easy  position  at  the  gun  the  best  results  will  not 
be  forthcoming.  Pointers  will  sometimes  select  cramped  po- 
sitions, with  wrong  eye  at  the  telescope,  hands  improperly 
placed  on  the  elevating  wheel,  etc.  All  of  these  must  be  cor- 
rected. It  may  not  be  sufficient  for  the  pointer  to  say  that 
his  position  is  the  easiest  for  hwi. 

(ft)  Continuous  aim. — Continuous  aim  does  not  mean  that 
the  line  of  sight  is  necessarily  held  on  the  target  during  the 
comi^lete  roll  of  the  ship,  but  it  means  that  the  gun  is  held 
accurately  pointed  throughout  the  firing  interval;  that  the 
wires  are  on  the  point  of  aim  and  not  moving  across  it  when 
the  firing  key  is  pressed.  This  is  essential  to  accuracy  when- 
ever a  gun  is  fired  from  a  rolling  platform.  The  feature  of 
maintaining  the  aim  during  the  complete  roll  is  an  element 
affecting  rapidity  but  not  accuracy  of  fire.  An  expert  pointer 
will  usually  hold  the  horizontal  wire  of  intermediate  and 
secondary  guns  on  the  target  while  the  gun  is  being  loaded, 
and  will  be  ready  to  fire  the  moment  he  receives  the  signal. 
The  necessity  of  attempting  continuous  aim  must  be  impressetl 
upon  all  pointers,  together  with  the  difference  between  main- 
taining the  aim  during  the  complete  roll  and  during  the  firing 
interval  only. 

(c)  Method  of  operating  gun. — The  elevating  pointer  of  a 
turret  gun,  where  it  is  necessary,  should  receive  training  in 
laying  his  gun  in  the  loading  position  after  each  shot,  so  that 
he  will  do  it  instinctively,  and  then  resume  his  position  at 
the  sight,  ready  (the  moment  gun  is  loaded)  to  pick  up  the 
target;  the  trainer  maintains  bis  aim  at  all  times. 


GUNNERY  INSTRUCTIONS.  26 

id)  Sight  setting. — Hitting  is  impossible  unless  the  sight 
setting  is  accurate;  rapidity  of  fire  is  also  impossible  without 
promptness  in  sight  setting;  hence,  it  is  essential  that  careful 
attention  be  given  this  matter.  In  setting  sights  there  should 
be  no  wasted  effort  or  time  due  to  the  sight  setter  raising  and 
then  lowering  the  sight,  and  vice  versa.  The  correction  should 
always  be  started  and  completed  in  the  direction  in  which  it 
has  been  ofdered.  When  a  correction  to  the  sight  has  been 
accomplished  it  has  been  found  advantageous  at  elementary 
practice  to  have  the  sight  setter  call  out  "set."  In  all  exer- 
cises of  the  pointer  group,  sight  setting  and  range  transmitting 
should  be  practiced,  and  the  sights  should  be  changed  without 
the  knowledge  of  the  pointer. 

(e)  Joint  training  of  members  of  the  gun-pointer  group. — 
In  view  of  the  fact  that  two  men  are  required  to  point  each 
broadside  gun  of  3-inch  caliber  and  above,  and  three  men 
constitute  a  set  of  pointers  for  a  turret,  it  is  important  that 
these  men  receive  as  much  practice  as  possible  when  working 
together. 

60.  Advantages  of  the  mechanical  devices. — Guns  rigged 
with  mechanical  targets  generally  work  with  greater  ease  and 
nicety  of  movement  than  others.  Several  mechanical  targets 
should  be  rigged  for  each  caliber,  and  these  should  be  shifted 
from  one  gun  to  another.  In  some  cases  the  difference  be- 
tween a  mount  which  has  had  considerable  mechanical  target 
work  and  others  is  so  great  that  the  exercise  loses  much  of 
its  value  when  the  trained  pointer  fires  his  own  gun  on  which 
a  mechanical  target  has  not  been  rigged.  In  so  far  as  prac- 
ticable, a  pointer  should  receive  all  training  at  his  own  gun. 
It  should  be  borne  in  mind  that  the  continuous  use  of  one 
gun  for  the  dotter  and  mechanical  targets  will  be  apt  to 
eventually  produce  lost  motion  in  the  gears. 

61.  Advantage  of  one  device  over  another. — Officers  gener- 
ally express  a  strong  preference  for  one  or  another  of  the  de- 
vices herein  mentioned  for  training  gun  pointers.    The  strong 


26  GinfNlEY  INSTEUCTIONS. 

arguments  that  are  heard  in  favor  of  each  show  conclusively 
that  there  are  good  reasons  for  the  employment  of  all  of 
these  devices.  There  are  many  times,  however,  when  one  may 
be  utilized  to  far  greater  advantage  than  another.  The  value 
of  any  of  these  methods  depends  on  the  intelligence  with 
which  it  is  used. 

DISADVANTAGES  OF  TRAINING  WITH  MECHANICAL 

APPLIANCES. 

62.  Pointers  trained  with  mechanical  appliances  failing 
on  target  practice. — Some  pointers  who  consistently  make 
good  scores  with  the  Morris  tube  and  dotter  sometimes  fail 
to  make  good  scores  at  practice.  This  is  due  to  a  variety  of 
reasons,  and  these  should  be  carefully  considered  by  the 
division  officer  in  deciding  whether  or  not  the  pointer  should 
be  continued  in  his  position. 

These  reasons  may  be  enumerated  as  follows : 

63.  («)  Mechanical  targets  do  not  test  the  nerve. — Skill 
in  pointing  consists  in  always,  not  sometimes,  having  the  gun 
accurately  pointed  when  fired.  The  pointer  whose  mind  is  oc- 
cupied with  dread  of  the  discharge  will  never  succeed  in  mak- 
ing a  good  score  when  firing  from  an  unsteady  platform. 

(6)  Mechanical  targets  do  not  test  the  obedience. — Im- 
plicit obedience  in  regard  to  the  point  of  aim  is  essential  to 
consistent  hitting.  The  temptation  for  a  pointer  to  aim  at 
some  other  point  than  at  the  point  designated,  in  order  to  cor- 
rect an  error  made  in  the  preceding  shot,  is  very  great,  and 
may  not  appear  to  a  great  extent  in  training. 

(c)  Perfunctory  training. — The  training  will  become  per- 
functory if  the  division  officer  does  not  exercise  vigilance. 
Training  with  mechanical  targets  may  be  carried  out  in  such 
a  manner  that  the  pointer  may  make  excellent  scores  by  firing 
"on  the  fly" ;  that  is,  when  the  line  of  sight  is  moving  more  or 
less  rapidly  across  the  target.    Good  scores  are  made  more 


GUNNERY  INSTEUCTIONS  27 

readily  with  mechanical  appliances  than  with  the  gun,  on  ac- 
count of  the  shorter  liring  interval,  and  also  because  the  mo- 
tion of  the  target  can  be  easily  anticipated.  Pointers  are  very 
often  assisted  by  a  fixed  background  which  acts  as  a  plane 
of  reference  on  which  to  estimate  the  motion  of  the  target. 

(d)  Regularity  of  motion. — A  ship's  motion  in  a  seaway  is 
irregular,  whereas,  pointers  are  sometimes  trained  with  a 
mechanical  target  on  which  ingenuity  has  been  expended  to 
make  motion  uniform.  The  target  is  rarely  moved  in  a  man- 
ner which  reproduces  the  motion  of  a  ship.  The  loss  in  both  ac- 
curacy and  rapidity  of  fire  is  frequently  due,  not  so  much  to  the 
difficulty  of  the  elevating  pointer  holding  on,  as  to  the  fact  that 
the  irregular  lurching  motion  interferes  very  greatly  with  the 
trainers.  Mechanical  targets  should  have  separately  operated 
training  and  elevating  gear.  Successive  rolls  should  not  be  of 
the  same  amplitude.  Yaw  should  become  quick  and  irregular 
as  the  training  progresses.  At  practice  with  mechanical  tar- 
get no  pointer  should  ever  be  allowed  to  fire  when  the  target 
is  steady  at  the  end  of  the  roll.  The  ship's  period,  both  for 
roll  and  for  pitch,  should  be  carefully  timed,  and  the  period 
for  the  mechanical  target  established  from  the  data  obtained. 
The  period  for  roll,  for  the  mechanical  target,  should  be  less 
than  that  of  the  ship.  Pointers  should,  if  practicable,  be 
trained  to  fire  at  all  times  during  roll. 

(e)  Failure  to  follow  throug'li. — It  is  frequently  the  case 
that  a  pointer  who  practices  successfully  with  mechanical  tar- 
gets will,  when  firing,  follow  only  until  he  wills  to  fire,  and 
fail  to  follow  throughout  the  firing  interval,  thus  insurii^  a 
miss  when  there  is  any  considerable  motion.  A  delayed  action 
in  the  firing  circuit  will  assist  to  correct  this  fault.  This 
delayed  action  should  be  variable. 

64.  Extreme  accuracy  in  pointing. — Attention  is  again  par- 
ticularly invited  to  the  necessity  for  carefully  training  pointers 
to  the  highest  possible  degree  of  accuracy  in  pointing.  Unless 
the  pointers  have  been  so  trained  that  we  can  always  rely 


28  GUNNERY  INSTEUCTIONS. 

upon  them  to  hit  within  a  small  space  when  all  of  the  condi- 
tions are  known,  it  will  be  impossible  to  develop  an  accurate 
fire  under  battle  conditions,  where  we  may  have  to  depend 
very  largely  upon  the  accuracy  of  the  pointers  to  determine 
the  most  difficult  of  all  of  these  conditions,  viz,  the  sight-bar 
range  of  the  enemy. 

65.  Besult  of  firing  when  not  on. — The  pointer  should  be 
made  to  realize  that  if  ho  fires  when  not  exactly  "  on  "  and 
following,  he  will  certainly  miss,  causing  a  delay  until  the  gun 
is  reloaded,  and  giving  the  spotter  an  incorrect  impression. 
When  the  gun  is  finally  reloaded  it  will  then  be  in  exactly  the 
condition  as  it  was  before  he  fired.  The  pointer  has,  there- 
fore, lost  the  entire  time  required  to  load,  aim,  and  fire  one 
shot,  not  to  mention  having  wasted  the  ammunition,  and 
Interfered  with  fire  control. 

66.  Necessity  for  skill  with  mechanical  targets. — Until  a 
man  has  acquired  skill  through  practice  with  mechanical  de- 
vices, there  is  little  use  in  his  attempting  to  fire  from  a  rolling 
platform.  Progress^  must  be  judged  by  results  and  not  by  the 
hours  of  training.  Some  men  acquire  expertuess  quickly, 
while  others  soon  show  that  it  is  a  waste  of  time  to  attempt 
to  train  them  as  gun  pointers. 

67.  Necessity  for  accurate  mechanisms. — Accurate,  quick 
work  with  mechanical  targets  is  impossible  with  faultji 
mechanism ;  division  oflicers  should  devote  the  greatest  atten- 
tion to  eliminating  the  lost  motion  in  their  mounts  and  sights. 
Before  attempting  drill  it  is  essential  that  the  adjustments  be 
exact.  Gun  should  be  weighted  at  breech  in  order  to  com- 
pensate for  the  absence  of  the  weight  of  the  projectile  and 
charge.  Otherwise  undue  load  is  thrown  on  the  elevating 
gear,  which  results  in  wear,  and  the  pointer  may  be  im- 
properly instructed  in  the  manipulation  of  his  mount.  (Plac- 
ing a  projectile  in  the  gun  is  sometimes  an  easy  way  to  over- 
come this  diflBculty.) 


GUNNERY  INSTRUCTIONS.  29 

68.  Progressive  training'. — The  dotter  and  Morris  tube  are 
Intended  to  train  men  to  a  high  degree  of  manual  dexterity  in 
handling  tlieir  guns.  The  motion  given  to  the  target  should 
always  be  kept  slightly  in  advance  of  the  skill  of  the  pointers 
until  they  have  attained  proficiency.  It  must,  of  course,  be 
slow  and  regular  in  tlie  beginning,  but  before  a  pointer  is 
expert  he  should  be  able  to  make  a  good  score  on  a  target 
whose  motion  is  both  irregular  and  rapid. 

THE  DOTTER. 

69.  Advantages  of  the  dotter. — The  advantages  of  the  dot- 
ter as  an  instrument  fur  the  training  and  practice  of  gun 
pointers  are: 

(1)  Training  with  it  may  be  carried  on  at  practically  any 
time,  especially  in  port  (or  at  sea  when  check  telescopes  can 
not  be  used,  see  art.  77). 

(2)  Small  inaccuracies  in  aiming  are  made  apparent  be- 
cause of  the  size  of  the  impression  made  by  the  dot. 

(3)  If  well  designed  and  made,  the  instrument  is  exceed- 
ingly accurate. 

70.  Variety  of  design. — Because  of  the  number  and  variety 
of  designs,  it  is  not  deemed  necessary  to  describe  in  detail  the 
various  types  of  dotters  used  on  board  ship.  Some  are  some- 
what complicated  in  their  details,  and  all  require  careful  ad- 
justment and  attention. 

71.  Delayed  action. — Attention  is  invited  to  the  desirability 
of  so  rigging  the  dotter  as  to  cause  it  to  delay  firing  after  the 
key  is  pressed,  which  necessitates  keeping  "  on  "  the  target 
during  the  firing  interval. 

THE  MORRIS  TUBE. 

72.  Function. — The  Morris  tube  affords  a  ready  mean.s  oi 
exercising  the  pointer  group.    It  is  clieap*  easily  rigged,  aud 


80  GUNNERY  INSTRUCTIONS. 

readily  adjusted,  but  is  not  as  refined  an  instrument  as  tlie 
dotter.  If  tlie  rifle  is  properly  mounted  tlie  siglit  setter  may 
be  given  drill  as  well  as  the  pointers. 

73.  Design  and  rig. — While  a  diversity  exists  in  the  method 
of  rigging,  the  diagram  shows  the  essential  features  of  the 
most  common  form. 

Briefly,  the  appliance  consists  of: 

(a)  A  miniature  target  carried  on  a  target  frame,  E,  at  the 
muzzle  of  the  gun,  which  is  capable  of  both  vertical  and 
latei-al  motion,  while  remaining  always  at  approximately  the 
same  distance  from  the  pointer's  eye  at  the  telescope,  D. 

(6)  A  small  rifle,  B,  is  rigidly  secured  to  the  great  gun, 
and  in  such  a  position  that  the  axis  of  its  bore  and  the  line 
of  sight  of  the  great  gun  intersect  at  the  miniature  target. 

(c)  A  bullet  stop,  A,  secured  to  the  muzzle  of  the  great  gun. 

74.  Turret  devices. — In  turrets  having  sights  mounted  other- 
wise than  on  the  trunnions  of  the  gun  the  Morris  tube  rifle 
must  move  parallel  to  the  line  of  the  telescope.  This  some- 
what complicates  the  design  of  the  device  for  turret  mounts. 

75.  Essential  features.— The  following  are  essential  fea- 
tures of  a  successful  Morris-tube  target: 

(1)  Elimination  of  vibration. 

(2)  Every  part  of  the  target  frame,  boom,  weights,  etc., 
should  be  heavy  and  substantial.  Weight  is  essential  in  order 
to  secure  a  steady  motion. 

(3)  The  elevation  and  train  of  the  target  should  be  entirely 
independent  of  each  other. 

(4)  The  guys  should  be  so  rove  off  that  they  will  not  cause 
a  jerky,  irregular  motion. 

(5)  The  target  should  move  very  slightly  for  a  considerable 
movement  of  the  cranks,  giving  the  vertical  and  horizontal 
motion. 

(G)  The  target  sheets  should  be  so  secured  as  to  minimize 
the  effect  of  vibration  caused  by  wind. 


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The  Morris-Tube  Target. 

Key  to  lettering  on  sketch.— Letters  .\  to  I  refer  to 
Intermediate  puns,  and  J  to  N  to  turret  guns.  A  is 
the  iron  b  x,  or  bullet  stop:  B,  clamp  for  small  rifle: 
D,  teleseope-sicht:  E,  target  frame;  F,  spar  or  boom 
carrying  target;  G,  small  pulley  for  boom  topping 
lift:  G',  reel  for  boom  topping  fift:  H-H,  transverse  i 

guys  passing  over  pulleys,  one  to  weicht  I,  the  other  to  reel  J;  J',  turret  telescope ; 
K,  bullet  stop  on  turret  guns:  L,  bands  on  the  chase  of  turret  guns  tor  securmg 
small  rifle;  M,  small  rifle  mounted  on  turret  guns;  N,  target  Irame  for  turret  gun. 


82  GUNNERY  INSTRUCTIONS. 

(7)  The  small  rifle  should  be  so  rigged  that  the  regular 
firing  key  of  the  gun  may  be  used. 

(8)  The  rifle  should  be  mounted  so  as  to  permit  it  being 
quickly  moved,  both  in  elevation  and  in  azimuth,  a  certain 
definite  amount  in  order  to  afford  exercise  for  the  sight  setter. 
In  this  case  the  bullet  stop  must  be  large  enough  to  catch 
bullets  fired  from  any  position  of  the  small  rifle,  the  motion 
of  which  should  be  limited  by  stops.  Reports  of  target  prac- 
tice show  that  one  of  the  chief  causes  of  poor  shooting  is  that 
the  sight  setters  had  been  instructed,  but  not  sufficiently 
trained  in  their  duties. 

(9)  The  electromagnet  should  be  so  fitted  as  to  delay  the 
fire  by  a  variable  amount  after  the  firing  key  is  pressed,  in 
order  to  force  the  pointer  to  practice  continuous  aim. 

(10)  The  minature  target  should  be  about  25  per  cent 
smaller  than  the  smallest  projections  of  the  target  which  it 
is  intended  to  represent. 

(11)  The  bore  of  the  small  rifle  must  be  kept  clean. 

THE  CHECK  TELESCOPE. 

76.  Advantages  of  check  telescope. — The  check  telescope 
is  a  most  excellent  means  of  training  and  of  discovering  the 
abilities  of  gun  pointers.  The  advantages  of  this  method  are 
that— 

(a)  It  may  be  utilized  at  .sea  if  ships  are  cruising  in  com- 
pany. 

(&)  No  special  apparatus  has  to  be  rigged. 

(c)  By  ob.sei'ving  the  principles  carefully  a  division  officer 
should  be  able  to  find  out  fairly  exactly  the  abilities  of  his 
pointers,  and  what  he  may  reasonably  expect  them  to  do  at 
t!irget  practice  before  a  shot  is  fired. 

77.  Check  telescopes  in  connection  with  mechanical  tar- 
gets.—Training  at  Morris  tube  and  dotter  may  be  regulated 
at  will  to  simulate,  to  some  degree,  any  desired  condition  of 


GUNNERY  INSTRUCTIONS.  33 

iiiotidii.  Witli  clicck-tficscope  traiuiii;,',  only  tlio  iiiolioii  on  a 
paitifular  day  is  availal)l('.  As  on  niauy  days  at  sea  flioro  is 
l>ra«'ti<'ally  no*inoiinn  in  liij^  ships,  overy  opportunity  for 
roupli-watcr  rjipfk-telesrope  work  sliould  he  taken  .-idvantage 
of.  Toloseoix's  with  chock  oyepiocos  are  very  valnai)lo  when 
used  together  witli  tlie  dotter.  r>y  utilizing;  the  check  sifiht 
lli<>  division  ollicei-  is  cnahied  to  watch  and  control  the  opera- 
tion of  tli(>  doKer.  and  to  study  the  methods  and  progress  of 
his  i)oinlers. 

78.  Types  of  check  telescope. — In  the  later  ships  the  point- 
ers" telescojies  ai'c  jtrovided  with  eyepieces,  to  he  used  in 
ciiecking  tlie  jxtintei-'s  w<u-k.  In  older  sliips  attachments  have 
l)een  .secured  to  tlie  sights  and  auxiliary  tele.scoi)es  mounted 
for  use  on  the  larger  guns.  With  the  secondary  guns  it  is 
sonit'linies  necessary  t"  use  bore  sights  for  checking  purposes. 

79.  How  mounted. — Check  telescopes  may  be  mounted  out- 
side on  the  t\u-ret  guns  themselves,  or  attached  to  the  pointer's 
sight.  .\  method  is  to  mount  three  telescopic  sights  as  fol- 
lows:  ( »ne  on  each  gun  on  a  hoiiziintal  arm  projecting  in- 
ward, and  a  third  on  u  vertical  .stand  on  top  of  the  turret  for 
use  in  cluM-king  up  the  trainer.  This  third  check  has  been 
found  exceedingly  useful.  These  "checks"  should  be  fitted 
with  easily  adjustable  thumbscrews  to  bring  the  ci'oss  wires 
on  with  the  jminters,  and  should  lu^  pi-otected  from  the 
weather  and  spray  by  suitable  coverings'.  By  means  of  the 
adjustable  thumbscrews  the  checks  can  be  brovight  on  and 
Ifore  sighted  with  the  jiointer's  sights  at  any  time,  and  with 
\ery  little  trouble;  of  course,  a  change  in  range  will  throw 
th(>  checks  out,  but  this,  however,  can  be  adjusted  in  a  very 
short  time.  It  is  important  for  the  officer  at  the  check  tele- 
scope to  be  in  easy  coinnmnication  with  the  pointer  so  that 
Ite  may  coach  him.  A  flexible  tube  .should  he  so  rigged  that 
the  officer  may  speak  into  one  end  of  it  while  looking  through 
the  check  telescope.    The  other  end  of  the  tube  should  be  close 

3477R — 1  s .3 


34  GUNNERY  INSTRUCTIONS. 

o  and  opposito  the  pointer's  ear.  A  buzzer  attached  near  the 
,'heck  telescope  outside,  and  connected  to  tlie  tiring  key,  an- 
lounces  to  the  officer  the  instant  when  tlie  trigger  is  pulhxl. 
iVhen  tlie  officer  is  in  direct  coniuiunication  witli  tlie  pointers, 

as,   for   instance,    wiien    inside   the   turret,    tlie   voice   tube   is 

unnecessary. 

80.  Necessity  for  firing  signal. — It  is  desiral)le  to  connect 
a  bnzzi'r  in  the  tiring  circuit  which  the  pointer  sounds  when 
coniiileting  liis  contact  on  tiring  and  wlicn  pi'operiy  laid  on 
the  target.  Signals  to  tire  .should  be  given  at  projjcr  part  of 
roll.  When  there  is  an  excessive  roll,  it  is  not  possible  to  be 
"on"  at  all  times  with  pre.seut  gear,  but  there  will  come  a 
time  of  comparatively  easy  motion  when  the  signal  should  be 
made.  Signals  should  not  be  given  at  regular  intervals  of 
time  and  should  not  be  given  oftener  than  the  time  required  to 
load  the  gun.  The  interval  between  stand-by  and  tire  shouhl 
not  lie  constant. 

81.  Conducting  exercise. — In  conducting  the  training  with 
check  telescopes  ves.sels  should  steam  on  parallel  courses,  each 
hoisting  a  target  of  predetermined  size  laid  out  in  rectangles. 
The  division  otlicer.  by  carefully  obsei'ving  the  work  of  his 
point(M-s  and  by  assigning  a  detinit(»  value  to  certain  rectangles 
in  the  poin.ter's  target,  is  able  to  assign  definite  scores  to  his 
men.  Three  officers  should  be  present  at  tnri-et  check  t tele- 
scope drill.  If  this  'is  not  practicable,  a  reliable  petty  officer 
may  perform  the  duties  of  an  officer  in  checking  up  and  scor- 
ing. Individual  score  cards  should  be  kept  for  each  man,  the 
result  of  Ills  .strings  accurately  recorded,  and  results,  with  a 
mark  of  efficiency,  posted  on  the  bulletin  board. 

82.  Necessity  for  keeping  scores. — By  keeping  scores  care- 
fully, like  batting  avei'agt's,  and  by  iiosting  them  on  the  bulle- 
tin boards,  interest  and  competition  are  stimidated,  and  a  very 
good  ide.-!  may  be  gained  of  th<'  work  of  the  pointers  an(l  what 


GUNNERY  INSTRUCTIONS.  36 

iii;iy   1»(>  cxitcctcil   of  tlnMii   willi   tlic  slil])   nilliii^'  and    pilcliiii;;' 
uikUt  various  (•(uiditidiis  of  sea  and  wontluT. 

SUBCALIBER  PRACTICE. 

8'i.  Value  of  subcaliber  practice. — Tliis  iiiaclicc  is  ni'  ^n-cal 
\alu('  al'tcr  a  (■crtaiii  aiinuiul  (if  sl-cill  in  Hiiiiitiii.u'  lias  l)eeii  al- 
taiiicd.  If  can-icd  dut  with  iintraiii(>d  pointers,  it  will  l»c 
foinid  (>r  less  maicriai  JK'noHt  tiian  otlierwisc.  Sulx-aiihcr  is 
a  nii'tliod  supiiltMucnt  al  to  and  advanced  beyond  tiiose  previ- 
ously desi-i-ilied.  but.  as  mentioned  al)ove.  it  is  an  essential 
pai't  of  battle  training.  Subcalibei-  iurnisbes  an  a.^ency  jier- 
mittinji-  iiractically  a  dress  rehearsal  of  a  battle  jiractiee.  ex- 
oreisiiif;-  siiindt  aneousl.v  the  fire-control  parties,  sjiotters,  si.ijht 
.setters,  and  oIIkm's  concerned,  as  well  as  the  .mm  pointers. 
Casualties  nia.\'  be  sinndati'd  :ind  drill  made  vvvy  I'ealistic. 
This  Jiractiee  can  be  held  al  any  time  two  oi-  more  shiiis  find 
themselves  to.i;ctlier  al  sea,  practically  without  re.uard  to 
weather  or  sjieed. 

84.  Necessity  for  accuracy  in  adjusting  pieces. — A  first 
essential  in  subcaliber  work  is  Ibat  the  smaller  jtieces  sliould 
be  accurately  bore  si,i;iited  with  the  lai\i;er  ones  to  which  they 
ai'e  attaclH'd. 

85.  Firing  connections. — The  subcaliber  jiieces  should  be 
fii'eil  by  direct  attacbmont  to  tlie  ordinary  fii-iiiir  connection. 
If  this  is  not  jxissible,  a  reliable,  (juick  means  of  .uivin.u'  tin' 
tirin.u'  siu'nal  to  (he  man  lii'lnu'  the  piece  slioidd  be  arran.i^ed. 

86.  Table  for  subcaliber. — The  follo\vin.tc  table  siiow.s  the 
ivin.ii'es  iit  which  the  an.i^les  of  fall  of  the  l-iiounder  correspond 
to  thu.se  of  the  larger  pieces  at  10,000  and  at  1,800  yards. 


36 


GUNNERY  INSTRUCTIONS. 


C'orre- 

Corre- 

(JllD. 

Range. 

Service 

Angle  of 

spnndinp 

Reduced 

Angle  of 

sponding 

I.  V. 

fall 

l-poiindri 

I.  V. 

fall 

l-pounder 

range. 

range. 

Yardu 

o 

/ 

o 

f 

14'745 

10, 000 

2,fi00 

0 

41 

1 ,  975 

2,000 

11 

52 

2,600 

l.-}"/35 

10.  000 

2,  000 

1.") 

12 

2,  9.50 

2.  000 

15 

12 

2. 950 

12"/50 

■   10,000 

2,900 

5 

21 

■      1,7.50 

2,100 

10 

42 

2,500 

12"/1') 

10,000 

2,700 

6 

1.5 

1,900 

2,  100 

10 

42 

2,  .500 

12"/4n 

10, 000 

2,400 

S 

04 

2,  1.50 

2,100 

10 

42 

2.  500 

10"/40 

10,  000 

2,700 

fi 

54 

2,  000 

2,  100 

12 

05 

2,  650 

8"/45 

10,  (K)0 

2,  7r)0 

7 

50 

2, 125 

2.  100 

13 

52 

2,800 

S"/35 

10,  000 

2,100 

13 

52 

2,800 

2,100 

13 

52 

2,800 

14"/4") 

1,800 

2,600 

0 

48 

600 

2,000 

22 

825 

13"A5 

1,800 

2,  000 

1 

26 

850 

2,000 

26 

850 

i2'7r)0 

1 ,  800 

2,  900 

0 

38 

500 

2,  100 

14 

7.50 

I2'74r, 

1 ,  800 

2,  700 

0 

45 

575 

2,  100 

14 

7.50 

12'740 

1 ,  800 

2.400 

0 

57 

700 

2, 100 

14 

7.50 

1()'740 

1 ,  soo 

2,  700 

0 

45 

600 

2,100 

16 

77.5 

8'74.5 

1,800 

2,  7.30 

0 

44 

600 

2,  100 

18 

SOO 

8'735 

1,800 

2,100 

1 

1 

IS 

SOO 

2,100 

18 

800 

THE  DRILL  GUN. 


87.  Function. — The  drill  f^un  pei-forins  four  distinct  func- 
tions : 

id)  Physical  training. — It  i.s  inlendod  iiriniMrily  a.s  ;i 
nicnns  of  i>li.vsic;il  triiininij;  for  tlie  loaders  of  internieiliate 
guns,  .so  (jiat  muscles  and  wind  will  he  eciual  to  tlu>  strain  re- 
(luired   in   hattle. 

( ')  I  Precision. — Incidentally  it  trains  individuals  to  expert- 
ness  in  Ihe  hest  and  quickest  method  of  liandlin.ii'  the  ammu- 
nition and  in  loadin,i;. 

((')  Team  work. — After  the  individual  loaders  are  exi)ert  it 
affords  an  excellent  method  of  traininu-  the  .gun  crew  in  pre- 
cision of  movement  and  in  the  avoidance  of  interference,  or 
in  ■'  team  work  "  while  loading. 

(d)    Saves  the  gun. 

88.  Method  of  use. — In  the  primary  training  the  shellnian 
is  instructed  how  to  hold  the  shell,  how  to  place  it  in  the 


GUNNERY  INSTRUCTIONS.  37 

lirct'cli,  ;iii(l    how   host    to   utilize    his   strtMii,Mii    in    siioviii.L;'   the 
pro.j(»('tiIo  home. 

89.  Character  of  drill. — The  slieiiiiiiiu.  haviuj^  rtn-eived  iiidl- 
vidiiiil  iiistnictlon  and  traininfi  in  what  may  be  termed 
"  form,"  should  then  l)e  exercised  with  tlie  j^uu  crew.s.  In  the 
besiiiinuy-  strinf^s  of  20  shell,  tlie  usual  number  loaded  in  a 
stiMiifi,  may  ]>i(»ve  excessive;  liowever,  shorter  strings  do  not 
p:ive  tlie  desired  training'  in  endurance,  without  whicli  rapidity 
will  (UM-rease  ai)precial)ly  after  a  few  rounds.  In  all  exer- 
cises with  the  drill  gun  tlie  time  of  loading  the  strings  should 
be  taken. 

90.  Importance  of  precision  of  movement  in  loading.- — Un- 
less sd-ict  attention  is  given  to  the  details  of  tlie  drill  of  each 
individual  shellman  at  tlie  drill  gun  the  desire  for  rapidity 
will  cause  Ihcni  to  neglect  precision.  Precision  of  movement 
must  at  all  times  be  insisted  upon;  it  will  be  obtained  only  by 
constant  atteiitictii  to  (he  details  and  in  gradually  eliminating 
small  delays  in  tlie  various  oi)erations  of  loading. 

91.  Removing-  burrs. — A  small  balf-rouml  tile  should  be 
provided  at  the  gun  for  the  purpo.se  of  removing  liurrs  when 
tiring,  and  members  of  tlie  crew  must  be  previouHly  instructed 
wlieiv  to  look  for  them  and  liow  to  carefully  remove  them 
witiioul  damage  to  the  breech  mechanism. 

92.  Loading  drill  for  turret  guns. — The  drill  gun  is  inap- 
plicaiile  to  turret  guns;  hence  for  these  the  training  must  be 
olitained  by  loading  the  actual  gun,  using  drill  and  target 
shell,  dummy  charges,  and  tired  primers. 

93.  Drill  shell. — The  i.ssue  of  brass  drill  shell  has  been  dis- 
continued, target  shell  being  furnished  in  tlieir  stead.  These 
shell  are  furnislied  with  bands  which  may  be  removed  if  so 
desired.  Siiars  are  fui-iiislied  for  both  turret  and  broadside 
guns,  which  are  used  to  iirevent  .sliell  dropping  through  the 
bore  wlien  the  muzzle  is  depre.ssed,  and  also  for  liacking  out 
shell  wliieli  may  stick. 


38  GUNNERY  INSTRUCTIONS. 

94.  Dummy  charges. ^ — Dummy  powder  charges  filled  with 
small  pieces  of  hardwood,  beans,  or  other  similar  material, 
should  be  used.  In  order  to  afford  the  necessary  training 
and  experience  in  loading,  these  dummies  should  be  made  to 
represent  as  nearly  as  possible,  in  weiglit,  shape,  size,  and 
ilexibility.  the  actual  charge. 

&5.  Loading  drill  in  connection  with  pointing  exercises. — 
Ivoading  drill  in  connection  with  Morris-tube  and  check- 
telescope    training    may    be    advantageously    practiced. 

DRILL   AT  THE  GUN. 

96.  Joint  exercise  of  crew. — As  the  meml)ers  of  tlie  gun 
crews  become  skilUul  in  their  individual  duties,  the  entire 
crew  must  be  exercised  at  its  own  gun.  After  details  have 
been  trained  independently,  turret-guns  crews,  handling-room 
ci'ew.'^,  annnunition  passers,  and  all  details  concerned  with  tlie 
operation  of  the  turret  unit  nuist  be  drilled  and  exercised 
together  in  their  duties. 

97.  Lost  motion  in  training  gear. — It  frequently  happens 
that  the  lost  motion  in  the  training  gear  of  guns  of  inter- 
metliate  caliber  is  so  great  tliat  in  closing  the  breech  the  plug- 
man  throws  the  pointer's  aim  off  the  target,  thus  delaying  the 
(ire.  This  lost  motion  should  be  dimiuished  as  much  as  pos- 
sible, and  the  pointer  should  accust(?m  himself  to  it  by  fre- 
quently requiring  the  plugman  to  open  and  close  the  breech 
plug  after  each  shot  at  Morris-tube  practice.  The  plugmau 
should  be  trained  to  close  the  plug  with  the  least  possible 
derangement  to  the  train  of  the  gun. 

98.  Necessity  for  giving  accurate  ranges. — Though  for  the 
purpose  of  instruction  fictitious  distances  may  be  necessary  in 
connection  with  the  objects  u.sed  as  a  target,  they  should  never 
be  employed  if  their  use  can  be  avoided.  The  valuable  power 
of  judging  distances  comes  and  improves  with  practice,  and 
officers  should  seek  to  improve  their  powers  in  this  direction, 
as  well  as  to  instruct  the  men  by  estimating  the  correct  dis- 
tance of  the  moving  objects  employed  as  targets. 


GUNNERY  INSTRUCTIONS.  89 

99.  Point  of  aim. — The  point  of  aim  coiiiiminiciited  to  the 
«un  pointers  sliould  be  well  defined  and  thoroughly  under- 
stood by  all  concerned.  Such  a  point  is  tlie  intersection  of 
the  horizon  and  the  stem  or  stern  of  the  enemy.  These  points 
sliould  he  generally  plainly  visible  to  all  guns.  It  is  desirabU 
to  standardize  the  point  of  aim,  and  in  firing  at  ships,  unless 
another  point  is  designated,  the  intersection  of  the  stem  witll 
the  water-line  will  be  considered  as  the  point  of  aim.  Pointers 
nuist  be  carefully  instructed  not  to  fire  wildly  if  they  have  losi 
the  object,  but  in  the  case  of  firing  at  an  enemy  who  is  en 
slu-ouded  in  smoke  the  horizontal  cross  wire  of  the  pointer's 
telescoiie  can  be  kept  on  the  horizon  and  the  vertical  wire  kept 
on  the  center  of  the  cloud  of  smoke,  or  on  a  mast  if  one  is 
showing  above  the  smoke. 

100.  Necessity  for  actually  laying  gun  and  setting 
sights. — When  at  drill,  men  must  never  be  allowed  to  pretend 
to  lay  a  gun.  Correct  sight  setting  is  of  the  first  importance, 
and  accuracy  in  setting  sights  must  be  given  great  attention. 

101.  Gravity  of  mistake  in  target. — Ofiicers  nuist  bear  in 
mind,  and  nuist  impress  upon  the  men,  tlie  gravity  of  the  mis- 
take of  aligning  the  sights  of  a  gun  on  a  wrong  target. 

102.  Target  practice — Function  in  the  system  of  train- 
ing.— Target  practi<-e  at  short  rangt'S,  while  necessary  to  the 
tiiial  development  of  a  gun  crew,  must  l»e  regarded  as  a  test 
(>{'  the  i)i-oficieiicy  which  has  been  atlaincd  i-athcr  llian  as  a 
iiictliod  of  training.  It  is  a  lurihixl  diily  in  the  sense  that 
after  a  liiorongh  ])relimiiiary  training  exiierience  at  actual 
firing  is  iie.cessary.  It  is  quite  possilile  for  crews  which  have 
received  thorongh  training  to  make  a  perfect  score  at  their 
first  elementary  in-actice.  Until  target  practice  has  been  held 
the  pointers  and  the  memliers  of  the  crew  have  not  had  the 
experience  requisite  for  their  assurance  under  service  condi- 
tions. Division  officers  should  take  advantage  of  firing  to 
note  the  men  who  become  unduly  excited,  who  appear  gun- 
shy,  etc.,  with  a  view  to  assigning  thera  to  duty  where  failings 


40  GUNNERY  INSTRUCTIONS. 

will  liuve  tliQ  It'u.st  (letriuientiil  effect.  The  tir.st  elementary 
target  practice  after  coimuissioiiing  should  be  of  great  value 
in  removing  from  the  gun  men  who  are  so  affected.  E.special 
attention  should  be  given  to  the  demeanor  of  the  pointers. 

103.  Elenmtary  target  practice. — Elementary  target  prac- 
tice is  held  at  short  ranges  with  screens  of  such  size  that  all 
properly  directed  shots  will  hit.  While  the  practice  is  pri- 
n;ari!y  a  le,st  of  the  iioiutei's  it  also  is  a  test  of  the  entire 
gun's  vi'vw  and  to  a  considerable  degree  measures  the  organi- 
zation and  eihciency  of  the  ship.  .Spotters,  other  officers,  and 
members  of  the  crew  are  given  experience  and  a  practical 
demonstration  of  fire  control  in  its  simplest  form.  Material. 
c(^mnuinications.  and  efficiency  of  gun  crews  are  tested  under 
conditions  more  severe  than  is  generally  the  case  at  longer 
ranges. 

104.  Development  of  elem^entary  practice. — In  the  begin- 
ning of  our  modern  developm^'Ut.  and  for  some  years,  this 
form  of  practice  was  the  only  one  in  which  ships  competed, 
and  it  was  held  in  smooth  water.  In  order  to  assure  otu'- 
selves  of  our  abilitie.s.  and  to  develop  skill  in  loading,  han- 
dling, and  jiointing  the,  guns,  antl  to  thoroughly  test  materials 
the  conditions  of  elementary  practice  should  be  severe, 
liough-water  conditions,  which  are  not  altogether  possible 
with  our  present  target  e!|iiii)ment.  are  desirable. 

105.  Unsatisfactory  performances. — The  cause  of  every 
unsatisfactory  i)erformance  at  target  practice  should  be 
definitely  detennin.t^d.  Only  by  such  invesrigatious  may  the 
sources  of  troul)le  be  discovered  and  elinnnated  and  i)rogress 
assured.  L'urther  ])rogress  in  gunnery  depends,  to  a  consid- 
erable degree,  on  the  seeking  out  aiul  elinunating  of  errors 
heretofore,  perhaps,  neglected  as  unimportant.  Iidormation 
i'e,garding  shots  that  miss  the  target  is  as  important  as  that 
regarding  those  that  hit,  proviiled  the  amounts  by  which  they 
miss  are  definitely  ascertained  and  the  causes  of  failures  to 
hit  determined.     (See  U.  S.  Navy  Regs.  1913,  art.  1G09  (b). 


CHAPTER  5. 

TRAINING  FOR  COLLECTIVE  GUN  FIRE— INDI- 
VIDUAL SHIP. 

The  best  protrition  (ii/niDst  on  nirmti's  fur  /,s  u  ircll-ilirccti'd  flic 
from  I/our  own  f/iins. — Farra;iul. 

106.  Historical. — The  history  of  \v:irs  iii(lic:i!es  tliat  duds 
or  fleet  actions  may  begin  at  high  ranges  whifh  may  be  re- 
duced l)e<-ause  of  the  desire  of  one  or  t)0th  antagonists  to  reach 
distances  which  will  be  "  decisive." 

The  manner  of  approach  and  the  questiun  of  ranges  can 
only  be  decided  according  to  the  conditions  existing. 

107.  Character  of  training. — Gunnery  training  must  l)e 
with  the  idea  of  making  hits  at  all  stages  of  an  action,  i.  e.. 
(i)  at  the  highest  i-anges.  (2)  when  the  range  is  rapidly 
changing,  and  (3)  when  the  range  has  been  decreased. 
Casualties  must  be  anticipated  and  demoralization  avoided  in 
any  and  all  of  what  may  become  the  phases  of  battle. 

108.  Protection  afforded  by  well-directed  fire. — jMucIi  will 
depend  upon  the  gaining  of  the  "initial  advantage."  There 
can  l)e  no  question  of  the  superiority  of  the  protection  afforded 
by  a  "well-directed  tire"  at  all  stages  of  the  battle.  If 
sudiciently  welt  directed  and  sustained  it  will  surely  result 
in  victory. 

109.  Collective  gun  fire  (individual  ship). — Excellence  in 
individual  gun  lire  having  been  attained,  a  consideration  of 
the  principles  governing  collective  gun  tire  for  a  single  ship 
follows.  This  becomes  a  question  of  utilizing  to  the  best 
advantage    a    number    of    individually    perfected    gun    crews, 

41 


42  GUNNERY  INSTRUCTIONS. 

which  resolves  itself  into  the  following:  (1)  Fire  control ;  (2) 
avoidance  of  interference  of  guns  and  interferences  incidental 
to  mixed  calibers;  (3)  ability  to  sustain  fire  despite  the 
casualtes  which  may  be  expected  in  action;  (4)  ammunition 
supply. 

110.  Necessity  for  coordination. — Success  on  the  day  of 
Wattle  will  not  necessarily  come  to  one  who  has  good  pointers, 
torpedo  crew,  or  an  excellent  fire-control  or  ship-control  party. 
All  of  these  must  he  not  only  skilled  individually  but  they 
must  be  so  coordinated  and  schooled  that  they  will  operate 
together  efficiently  under  any  nr  all  of  what  then  may  become 
conditions. 

111.  Fire  control. — This  involves  a  knowledge  of  the  sight- 
liar  ranges,  of  the  individual  errors  of  gun  and  indices  of 
powder,  and  the  jironipt  tran.smission  of  the  range  and  battle 
ordeis  to  the  battery.  A  sufficient  supply  of  annnnnition  to 
the  guns  and  ability  to  sustain  fire  despite  casualties  and  a 
liroi)er  handling  of  the  ship  are  also  essentials  to  proper  fire 
control. 

112.  Notes  on  spotting  and  fire  control,  published  by  tiie 
(leiiarlmeiu  of  ordnance  and  gunnery  at  the  Naval  Academy, 
c<»ntains  a  description  of  the  apparatus  and  methods  eni- 
jiioypd  in  llie  fire  conli-ol  in  l)attleslii](S  at  the  present  time. 
Wlule  change  and  constant  improvement  may  be  expected  in 
methods  as  material  is  develoi)ed  the  princi])les  will  remain 
the  same. 

113.  The  sig-ht-bar  range. — A  first  e.sseutial  to  successful 
fire  conti-ol  is  that  the  range  finders,  or  means  of  discovering 
the  range,  .should  be  accurate  and  reliable.  The  errors  of 
gunfire  shoidd  be  reduced  to  a  mininuun  and  allowed  for  in 
assigning  the  sight-bar  ranges.  This  latter  would  probably  be 
accomplished  by  firing  trial  or  calibrating  shots  when  expect- 
ing and  preparing  for  a  battle.  In  determining  the  ballistic 
corrections,  the  loss  of  velocity  due  to  erosion  as  well  as  the 


GUNNERY  INSTRUCTIONS.  43 

cornH-tious   for   itMupeiiitui-c   niid   liei{,iit  of  hiiroiiK'ter   should 
be  considered. 

114.  Dispersion. — Proper  fire  control  is  inipossil)le  if  the 
dispt'i-siou  is  excessive.  With  excessive  dispei-sions  the  spotter 
is  helpless.  A  ]»roper  iH-rceiita.i;e  of  shots  may  l)e  Icept  falling- 
in  I'roiil  i>t'  tlie  tar.t;el,  ar.d  l)ut  few  lilts  made.  If  in  sucii  cases 
llic  (Icllcction  is  ^iood  and  tlio  dispersion  is  in  i-an.i;e,  the  short 
siiols  will  obscure  the  otliers  and  nothiut;-  definite  can  he  de- 
termiueil  by  those  cluirsied  with  tlie  tire  control  regarding 
the  ship's  performance. 

115.  Point  of  impact. — It  is  fundamental  that  all  pointers 
that  ai-e  under  the  same  control  xise  tlie  same  iiolut  of  aim. 
which  must  Ix'  well  defined.  'I'lie  iKiinl  of  aim  may  he  con- 
sidered to  lie  llu-  point  at  which  the  jMiinters  lay  their  pieces. 
It  should  lit'  distinginshed  fi'dUi  the  point  of  Iniiiact,  which  is 
the  point  at  which  the  projectiles  fall.  liy  varying  the  range 
or  ihe  deflection  on  the  sight,  the  iM)int  of  iini)act  may  l>e 
made  to  diffci'  widely  from  the  point  <d'  aim.  The  point  of 
;iim  should  be  well-defined  and  visible  at  all  times  and  remain 
unchanged.  It  might  he  e.xceeilingly  undesiralde  to  direct  the 
pieces  at  the  point  of  impact  as  then  the  Interference  due  to 
splash,  biu-stiug  of  shell,  etc..  would  have  a  very  considerable 
influence  on  the  rai)idlty  and  accm-acy  of  the  lire. 

116.  Procedure  in  opening  fire. — It  Is  absolutely  essential 
in  collective  tire  that  a  definite  pi-ogram  which  has  l)een 
Ihoroughly  drilled  for  and  rehearsed  slutuld  obtain.  \\'hen  it  is 
decided  to  begin  ranging,  ranging  .shots  should  be  fired  by  guns 
in  succession  as  rapidly  us  sight  corrections  nuiy  he  obtained 
and  applied,  and  tl)e  fire  slnndd  be  proceeded  with  without 
loss  of  time,  every  elfort  being  exercised  to  get  on  the  target 
without  delay.  Conditions  of  atmosphere,  sea,  weather,  etc., 
will  tletermine  the  range  at  which  fire  may  lie  opened.  The 
sequence  and  methods  of  firing  the  ranging  shots  should  be 
thoroughly  understood.  Tl\e  sight  setting  must  be  quick  and 
accurate,  the  sights  of  all  guns  bei'ng  Icept  set  together  and 


44  GUNNERY  INSTRUCTIONS. 

the  entire  battery  kept  in  band  prepureil  to  deliver  u  salvo 
tlie  instant  tliat  the  raufiiag  sliots  indicate  tliat  Hre  may  be 
(spencd  wirli  reasonaljle  expectation  of  hittinj;.  Wlien  once  the 
target  is  found,  the  training  should  he  such  that  rapidity  of 
hitting  will  he  assured. 

117.  Importance  of  the  initial  advantage. — The  first  .salvo 
delivered  in(o  an  opponent  insjjires  conttdence  on  the  one  side, 
and  conseciuent  coolness  and  deliberations  in  all  the  details  of 
tire  control  and  of  serving  the  guns,  together  with  steadiness. 
and  i-apidity  in  pointing.  On  the  other  hand,  the  ship  hit 
hard  in  the  early  stages  of  an  engagement  is  sure  to  be  thrown 
into  more  or  less  confusion,  and  thereafter  labors  under  a 
great  disadvantage. 

118.  Rapidity  of  hitting. — ///  thv  truiitUni  for  battle  titc 
tilt jjorta lice  of  tlte  rainditii  of  hitting  nith  turret  as  well  as 
other  fiuns  iiivst  not  be  overlooked.  In  long-range  target  pi'ac- 
tiee  with  a  small  ammunition  allowance  there  is  a  natural 
tendency  to  hold  the  fire  in  order  to  permit  the  spotting  of 
each  salvo.  This  practice  might  be  objectionable  in  battle. 
The  tire  should  be  slow  until  the  sight  bar  range  is  deter- 
mined, when  the  enemy  should  be  overwhelmed  with  a  volume 
of  fire  which  should  be  slowed  or  checked  when  spotting 
again  becomes  necessary.  Excessive  spotting  is  objectionable, 
as  it  slows  the  fire  and  tends  to  confuse  the  fire  control. 

119.  The  chief  fire-control  officer. — The  officer  controlling 
the  fire  must  be  of  quick  decision,  and  have  a  thorough  un- 
derstanding of  the  methods  to  be  followed  and  of  what  is  to 
be  accomplished.  It  is  equally  important  that  battery  officers 
should  be  perfectly  fannliar  with  the  plans  of  the  fire-control 
officer.  The  control  officer  should  be  in  touch  with  the  spotter 
and  with  what  is  going  on  in  the  stations  below,  so  that  he 
may  be  assured  that  the  directions  for  the  control  of  fii'e  are 
being  correctly  interpreted.  He  must  be  near  the  captain 
in  order  that  tlie  fire  control  may  be  coordinated  with  the 
ship  control. 


GUNNERY  INSTKUCTIONS.  45 

120.  Firing  signals.— Firiiij,'  sij::nals  are  givt-ii  uiuU-i-  I  lie 
(lii-ection  of  the  diief  fire-control  otTicor.  Their  frequency  de- 
Iiends  upon  ran^'e,  motion  of  sliii),  interference  by  smoke  and 
blast,  visibility  of  the  target,  and  the  time  required  for  spot- 
ting, and  setting  sights.  The  instant  for  giving  tiring  signals 
depends  upon  the  roll,  pitch,  and  yaw  of  the  ship.  Pitch  and 
yaw  are  more  difficult  to  contend  with  in  gun  pointing  than 
the  roll.  If  it  is  not  desired  to  wait  for  one  of  the  periodical 
intervals  when  the  ship  is  practically  steady  as  regards  pitch- 
ing and  yawing,  the  signal  to  fire  should  be  given  at  that 
part  of  the  pitch  when  there  is  least  angular  motion  of  tlie 
ship  in  the  vertical  plane,  and  the  least  yawing.  With  some 
ships  this  time  is  found  to  l)e  when  the  bows  are  buried  in 
the  sea.  In  this  case  the  signal  io  fire  f<ltould  be  ijlven  just 
before  the  downward  motion  ceases.  In  this  connection  at- 
tention is  called  to  the  error  caused  by  tiring  guns  when  tlie 
planes  through  their  trunnions  are  at  varying  angles  to  the 
jiorizontal.  If  there  is  not  much  pitching,  attention  should 
be  concentrated  on  the  part  of  the  roll  on  which  to  fire.  The 
signal  to  fire  sliould  nerer  he  (jiven  at  the  very  end  of  the  roll. 
M'hen  there  is  niueh  roll,  the  proper  time  to  give  the  signal 
is  just  before  the  motion  eeases  at  the  end  of  the  roll.  If  a 
firing  signal  is  sounded  at  the  finish  of  the  roll  or  pitch  the 
reversal  of  motinn  of  the  ship  will  surely  throw  some,  or  all 
of  the  pointers  off  the  target.  The  salvo  signal  entends  a 
strong  temptation  to  a  pointer  to  tire  whether  he  is  "  on  "  or 
not.     This  must  not  be  overlooked  in  training. 

121.  Elasticity  of  control.— The  fire  control  fails  if  it  is  not 
elastic,  pernntting  the  fighting  of  the  guns  of  the  ship  with 
a  centralized  control  over  several  lines  of  communication. 
.\fter  all  these  Hues  fail,  the  training  should  permit  the  guns 
to  continue  the  fight  independently.  Probably,  in  this  case, 
the  range  will  have  been  greatly  decreased.  The  installation 
and  system  of  training  should  enable  a  vessel  to  concent late 


46  GUNNERY  INSTRUCTIONS. 

(11-  to  divide  Iut  tii-o.  iis  cither  or  botli  of  tliese  are  posssibilities 
of  battle. 

122.  Detriments  to  fire  control. — Irre^iilarilies  of  spiked  or 
-our.se  are  directly  felt  in  the  tire  control.  Both  these  slow 
the  tire  down  as  well  as  militate  against  accuracy.  Funnel 
smoke,  splash  of  shell,  noi.se,  sun  .i,dare,  wind,  sea,  and  motion 
of  shi])  all  have  to  be  considered.  Conditions  as  they  exist 
must  be  taken  into  account.  Excessive  speed  may  cause  difR- 
(iiities;  a  ship  may  be  able  to  tight  when  running  to  leeward, 
wlKMi  it  would  be  impossible  to  do  so  otherwise. 

123.  Interference  of  guns. — The  interference  of  one  gun  or 
tii!-i-et  with  those  adjacent  is  to  some  degree  unavoidable.  In 
the  all-big-gun  ships  this  interference  generally  is  a  minimum, 
and  it  becomes  maxinmm  in  the  vessels  with  superposed  tur- 
rets and  mixed  batteries.  The  interferences  are  due  to  blast 
as  well  as  to  smoke  and  gas. 

124.  Method  of  overcoming  interferences. — In  order  to 
overcome  the  dithculties  incident  to  interferences  various 
methods  are  employed  for  collectively  tiring  tlie  turret  guns 
at  long  range  at  target  practice.  They  may  be  enumerated  as 
follows  : 

125.  I.  Independent  fire. — :\Iaking  the  "  stand-1)y  "  and 
tiring  signals  at  short  intervals  as  the  ship  steadies  at  the  end 
of  each  roll  -.mh]  allowing  pointers  to  fire  independently  when 
they  ai-e  on  the  target.  This  method  would  probably  be  the 
only  one  possible  at  present,  if  the  ship  has  much  motion  or  if 
the  salvo-signaling  system  fails.  With  it  a  system  of  local  tur- 
ret control  must  be  established  which  will  obviate  in  each 
turret  the  interference  of  one  gun  with  another.  With  these 
cared  for  tlie  interferences  of  one  turret  witli  the  next,  which 
may  be  considerable  at  times,  have  still  to  be  considered. 
Under  normal  conditions  single-barreled  salvos  should  insure 
a  rapid  tire  which  may  lie  well  controlled. 

126.  II.  Firing  both,  guns,  trusting  one  pointer  to  be  on.— 
Firing  turret  guns  on  a  common  firing  circuit   (double-bar- 


GUNNERY  INSTRUCTIONS.  47 

rt'letll.  diR'  poiuUn-  Hriiiii  both  suns  and  chtsing  both  tiriug 
circuits,  tlio  "off"  pointer,  having  nothing  to  do  with  the  fir- 
ing, is  able  to  concentrate  his  attention  on  tlie  laying  of  the 
piece  in  elevation.  The  firing  signals  may  be  made  at  short 
interval.s,  but  the  general  practice  in  ships  that  have  used 
Ibis  system  has  been  to  lengthen  the  periods  between  signals, 
and  to  endeavor  to  fire  as  many  turrets  as  possible  each  time 
a  signal  is  given. 

This  method  of  tiring  is  illogical  as  soon  as  the  motion  is 
such  that  a  pointer  has  any  difficulty  in  laying  exactly  on 
bis  target.  As  a  rule  the  primer  firing  intervals  are  suffici- 
ently regular  to  insure  the  guns  going  practically  together,  and 
one  gun  does  not  kick  the  other  off.  With  this  system  salvos 
of  the  entire  battery  become  possible. 

127.  The  following  objections  may  be  raised  to  the  plan: 
(ft)  If  the  firing  signals  are  given  at  long  intervals,  some- 
thing may  occur  to  interfere  with  a  signal,  and  so  expose 
the  vessel  as  a  target  for  considerable  periods  witliout  that 
protection  which  is  afforded  by  a  well-delivered  firm  from  her 
own  guns. 

{!))  If  one  or  more  pointers  are  unsteady,  the  efficiency  of 
the  control  may  be  seriously  impaired.  This,  however,  is  true 
of  any  system. 

(c)  It  may  encourage  the  violation  of  the  first  principle  of 
gunnery  :  "Never  fire  a  gun  unless  it  is  exactly  and  properly 
pointed." 

(d)  Firing  so  many  guns  together  may  accentuate  the  roll- 
ing of  the  ship  appreciably. 

128.  III.  Firing'  both  guns  when  both  pointers  are  on. — 
Firing  turret  guns  on  a  common  circuit  so  that  one  or  either 
pointer  fires  both  guns,  provided  the  other  has  his  circuit 
closed  or  makes  a  signal  that  he  is  on  the  target. 

This  is  a  more  logical  plan  than  the  one  described  above, 
and  more  closely  follows  the  principles  which  are  to  be 
always  impressed  on  pointers. 


48  GUNNERY  INSTRUCTIONS. 

129.  Objections  to  this  plan: 

(o)    ir  iieco.s.><itate.s  n  somewhat  (■oini)li<'iit<Ml  (irins  rircnit. 

(/))  Tliere  may  be  an  element  of  danger  in  tliis,  as  in  the 
plan  previou.sly  described,  if  efficient  .salvo  latches  are  not  px'o- 
vided  which  effectively  prevent  the  ojiening  of  a  breech  iniless 
the  gnn  has  fired.  Otherwise  a  hangtire  (m-  niisfii-e  might  cause 
lo.ss  of  life  ami  disaster. 

130.  IV.  Using  a  firing  pointer. — A  jilan  U<y  liring  turret 
guns  whicli  was  found  successful  on  a  recent  pra<-tice  was 
that  of  having  the  guns  fired  by  an  officer  when  both  elevating 
pointers  reported  that  they  wei'o  on.  An  othcer  looking 
through  a  telescope  tbat  was  correctly  set  in  train  tired  both 
guns  through  a  common  tiring  circuit.  TIk^  regidar  turret 
oflicer  should  not  perform  this  duty. 

131.  V.  Using  cross-connecting  device. — In  newer  shijis  a 
cross  connection  in  the  elevating  gear  permits  one  jxtinter  to 
lay  both  guns  in  elevation.  This  furnislies  the  simiilesf 
method  of  laying  turret  guns  for  double-barreled  salvos. 

132.  Methods  to  be  followed. — A  ship  should  be  prepared 
to  make  the  best  of  any  condition,  and  to  this  end  slioidd  be 
ti'ained  to  fire  iier  turret  guns  either  double-barreled  or  in- 
dependently, as  well  as  to  control  tlieir  hre  either  collectively 
and  centralized  or  individually  and  locally. 

133.  Broadside  guns. — With  broadside  guns  in  l;ii-go  ships 
the  accejited  method  of  collective  fire  is  in  salvo,  eacji  jxiinter 
tiring  his  own  piece  if  properly  on  the  target  when  the  signal 
is  sounded.  Salvo  tiring  reduces  to  a  inininunn  the  mutual 
interferences  wliich  are  of  particular  moment  with  guns 
moimted  in  this  way.  For  toi-pedo-defense  purjioses,  in  some 
vessels  the  salvo  signals  for  all  torpedo-defense  gims  are  rung 
from  one  station.  Contact  makers  at  the  various  defense  con- 
trol stations,  thrown  in  oi'  out  by  the  group-control  officers, 
cause  the  signals  to  be  sounded  or  not  to  be  sounded  at  the 
guns  belonging  to  their  group  or  groups,  according  to  whether 
or  not  it  is  desired  that  these  guns  be  fired  with  the  others. 


GUNNERY  INSTRUCTIONS.  49 

134.  Intermediate  guns  with,  turrets. — The  firing  of  inter- 
mediate guns,  togetlier  witli  those  of  tlie  major  caliber  in  ships 
of  (he  predreadnaught  cUiss,  is  a  question  of  considerable 
moment.  Data  would  mal^e  it  appear  that  at  about  10,000 
yards  a  small  percentage  of  hits  may  be  expected  from  these 
intermediate  weapons,  which  increases  rapidly  as  the  range 
is  sho)-te)i<vl.  It  would  pr<il)al)]y  not  be  expedient  to  attempt 
to  utilize  (lie  intermediate  l)attei-y  beyond  10.000  yards,  and 
(lie  crews  should  be  kept  in  reserve  until  this  range  is  reached. 
\Viien  tire  wi(h  the  int(>rniedi:ite  gmis  is  commenced,  these 
must  not  !)(»  a]h)wed  (o  sh)w  or  interfere  with  the  fire  of  the 
major  calibers.  If  a  long  firing  interval  is  used  for  turrets, 
the  intermediate  guns  may  be  fired  between  turret  «alvos. 
otlierwise  if  short  salvo  intervals  are  used  tliey  should  be 
lired  together  with  the  turret  guns. 

135.  Individual  control. — The  training  siiould  permit  the 
control  of  (he  fire  of  l)roadside  guns  individually,  as  well  as 
collectively,  by  night  or  day,  and  gun  rnplains  iind  reliable 
I)etty  officers,  as  well  as  division  oHicers.  nnist  understand  the 
methods  to  be  followed  in  spotting  and  in  fire  control. 

136.  The  spotter. — The  spotter  occupies  a  most  important 
station,  and  much  depends  on  the  cool,  good  judgment  of  this 
officer,  which  must  be  developed  by  long  experience  and  drill. 
He  should  know  his  range  and  ballistic  data  and  must  al.so 
have  the  heights  and  lateral  distances  between  conspicuous 
points  and  other  dimensions  of  his  target  fresh  in  his  mind, 
that  these  may  assist  him  to  quickly  find  and  hold  the  target. 
A  spotter,  in  his  training,  should  not  lose  sight  of  the  differ- 
ences that  will  be  presented  in  the  methods  necessary  when  fire 
is  directed  at  a  hull  and  not  at  a  target  screen. 

137.  Ability  to  sustain  fire. — An  ability  to  stand  punish- 
ment is  built  into  the  ship  in  so  far  as  practicable,  and  con- 
stant effort  is  being  made  to  improve  the  defensive  qualities 
of  vessels.     The  deciding  factors  in  coming  naval  battles,  as 

34776—18 4 


50  GUNNERY  INSTRTICTIONS. 

have  been  in  those  of  the  past,  will  be  accuracy  and  volume 
of  fire,  which  will  only  be  insured  by  the  morale  of  the  men 
engaged.  This  morale,  which  will  insure  the  fighting  of  the 
ship  as  long  as  she  remains  alloat,  is  unconquerable,  will  in- 
sure victory,  and  can  be  gained  only  by  constant  drill  and 
preparation  for  action.  AVhile  the  primary  means  and  de- 
vices for  supplying  anununition  and  for  directing  guns  should 
receive  the  greatest  attention,  the  auxiliary  devices  and 
methods  should  not  be  overlooked. 

138.  Ammunition  supply. — The  question  of  ammunition 
supply  in  action  should  be  carefully  considered.  The  supply 
of  sliell  and  powder  from  the  magazine  to  the,  gun.  the  opening 
of  the  boxes,  and  the  disposal  of  tlie  l)oxes  and  cases  must  all 
be  provided  for.  It  may  frequently  l)e  possible  to  improve 
the  chains  of  supply  and  to  facilitate  the  careful  handling  of 
all  classes  of  ammunition.  It  should  be  reme,mbereil  th;it 
anniumitiou  nuist  not  be  permitted  to  accmnulate  in  exposed 
positions,  as  it  then  constitutes  a  serious  source  of  danger. 

139.  Drill  of  amniunition  crews. — There  have  been  numer- 
ous instances  at  target  practice  where  a  turret  crew,  otherwise 
well  drilled,  failed  to  make  a  ci'editable  performance  because 
of  a  mistake  on  the  part  of  the  handling-room  crew.  The 
use  of  a  wrong  index  may  well  cause  misses  that  would  result 
in  disaster  in  action  ns  it  has  in  failure  at  target  practice. 

140.  Importance  of  minor  details. — No  detail  of  the  drill 
and  development  of  the  fire-control,  gun,  and  handling-room 
crews  is  .so  slight  as  not  to  merit  attrition. 

141.  Day  individual  practice. — The  training  of  the  col- 
lective tire  of  single  ships  is  tested  at  individual  ship  prac- 
tice in  so  far  as  it  is  practicable  to  do  so.  With  the  present 
facilities  we  may  measure  performances  at  various  ranges, 
but  it  is  dilHcult  to  devise  problems  which  will  test  the  ability 
to  make  hits  employing  the  entire  battery,  with  a  rapidly 
changing  range.  The  ranges  prescribed  for  day  individual 
practices   are  long   in   orde.r  that   training  may   be  with   the 


GUNNERY  INSTRUCTIONS.  61 

view  of  sccuriii.u  the  "  initial  advaiitaf,'^  "  and  iu  order  to 
make  condidons  most  severe.  It  must  not  hr  assumed,  how- 
ever, tliat  it  is  necessarily  the  case  that  a  battle  of  the  future 
will  l)e  finally  decided  by  a  cauuqnade  at  lon.i:  raii^e.  The 
conditions  of  range  can  no(  be  foretold,  anil  Ir.aininR  must 
antici|iale  all  of  wlial  may  become  the  idiases  of  an  engage- 
ni(>nt. 

142.  Casualties. — Casualti(>s  are  inlrodnced.  as  the  outcome 
of  battle  may  depend  on  tlie  manner  in  which  these  are 
bandied  as  well  as  on  the  gunnery. 

143.  Artificiality. — Constant  care  should  be  exercised  to 
a.void  artificiality  in  any  or  all  forms  of  lire  coutrol,  ship 
handling,  or  dealing  with  casualties. 

144.  Collection  of  data  and  analysis  of  results. — As  im- 
]ii'ovem(Mit  ill  gunnery  is  deiiende.nt  on  improvement  in  the 
precision  of  our  guns  as  well  as  in  control  of  lire,  all  data 
bearing  tlierecui  should  be  carefully  collected  at  target  prac- 
tice. The  results  of  practices  should  be  thoroughly  an- 
alyzed. The  time  taken  to  get  "  on  "  the  target  after  the  order 
to  "  oi)en  tire"  is  given,  the  "dispersion  in  salvos."  and  the 
"distance  of  the  mean  impact  of  salvos  from  the  target"  are 
all  matters  of  importance  in  measuring  a  ship's  performance 
at  long-range  practice  as  well  as  the  number  of  shots  hitting 
the  target. 


CHAPTER  6. 

TRAINING  FOR   COLLECTIVE  FIRE— SEVERAL 

SHIPS. 

145.  Collective  gunfire  (several  ships). — The  effective  con- 
trol of  tlie  collective  gunfire  of  sevei*al  ships  is  impossible 
unless  the  battery  of  each  ship  can  be  handled  efficiently. 
With  this  attained  for  vessels  individually,  the  control  of  the 
fire  of  all  may  be  accomplished. 

146.  Necessity  for  prearranged  program. — When  vessels 
fire  collectively  there  is  absolute  necessity  for  a  prearranged 
program  of  the  order  and  methods  of  firing,  etc.,  which  is 
thoroughly  understood  by  all  officers  concerned.  The  scheme 
by  which  the  fire  of  vessels  of  a  force  is  distributed  should 
form  an  important  part  of  the  battle  plan  of  a  commander  in 
chief.  Once  the  general  principles  are  understood  and  the 
methods  worked  out.  the  control  of  thfe  fire  of  individual  ships 
should  be  left  in  the  hands  of  the  captains,  each  of  whom  is  in 
a  position  to  be  the  judge  of  how  his  fire  may  be  directed  with 
the  greatest  effect. 

147.  Interferences  with  gunnery. — Signals  and  directions 
from  outside  sources  during  an  engagement  make  for  con- 
fusion. When  fleets  are  locked  in  gunfire  the  one  that  persists 
with  the  least  interruptions  and  interferences  and  compels  its 
adversary  to  give  way,  maneuver,  or  modify  its  fire  delivery, 
should  win,  other  things  being  equal.  There  must  always  be 
loss  of  fire  delivery  due  to  rapid  changes  of  course  or  speed 
or  incidental  to  a  shift  of  target.  Prom  a  gunnery  standpoint 
a  ship  is  in  position  when  she  is  able  to  make  full,  effective 
use  of  her  battery,  and  does  not  interfere  with  the  fire  of 
other  vessels  in  the  formation.  A  methodical  exactness  of 
position  and  formation   within  reasonable  limits  is  unneces- 

52 


GUNNERY  INSTRUCTIONS  63 

Kury  to  this  end.  Sudden  attempts  to  gain  or  lose  distance 
invite  disaster,  in  tliat  tliey  may  cause  shots  to  miss  that 
would  otherwise  be  effective,  and  interferences  may  occur, 
such  as  the  lifting  of  a  safety  valve,  excessive  smoke,  or 
crowding:  of  another  vessel. 

148.  Firing-  at  the  wrong-  target. — Results  at  target  prac- 
tice make  it  appear  that  there  is  serious  probability  of  a  mis- 
take being  made  in  the  targets  by  a  part  of  the  battery  of  a 
tiring  vessel.  The  likelihood  of  such  mistakes  would  be  en- 
hanced in  battle  if  ships  in  the  enemy's  line  were  similar  in 
appearance.  A  mistake  of  target  by  a  turret  or  turrets  would 
invite  disaster,  the  likelihood  of  which  must  be  fully  appre- 
ciated, and  the  necessary  precautions  must  be  taken  to  avoid 
such  an  error.  If  a  ship  tire  at  a  wrong  target,  one  of  the 
enemy's  ships  may  be  left  not  under  fire,  and  the  spotting  of 
another  ves.sel  firing  at  liei-  proper  target  wi  !  l)e  seriously 
interfered   with. 

149.  Concentration. — When  several  ships  concentrate  on  a 
single  vessel,  the  ability  of  the  latter  to  deliver  an  effective 
tire  is  disturbed  by  the  fact  that  aside  from  the  destructive 
effect  of  the  enemy's  shot,  which  rapidly  lessens  the  effective- 
ness of  her  own  fire  delivery  as  well  as  reduces  her  defensive 
strength,  she  has  several  targets  at  which  to  direct  her  guns. 
Concentration  should  not  be  attempted  unless  all  of  the 
vessels  of  an  enemy  that  may  fire  are  covered.  Conditions  in 
the  course  of  a  battle  may  make  one  force  of  the  two  that 
began  the  engagement  with  equal  numbers,  temporarily,  nu- 
merically the  superior  in  vessels  that  may  effectively  utilize 
their  batteries.  On  such  an  occasion  concentration  should  be 
restored  to. 

150.  Conditions  permitting  concentration. — For  vessels  to 
oont'entrate  effectively  at  long  range,  it  is  necessary  that  they 
should  fire  in  salvo.  If  a  maximum  of  fire  is  to  be  delivered, 
these  salvos  should  be  from  all  the  guns  bearing.  In  other 
words,  the  maximum  weight  of  metal  should  be  delivered  la 


54  GUNNERY  INSTEUCTIONS. 

each  stUvo.  By  firing  full  salvos  in  rotation  in  tliis  way  sliips 
may  identify  and  so  control  the  fall  of  their  own  projectiles, 
and  the  target  is  cleared  between  salvos.  As  full  salvos  are 
necessary  for  effective  concentration,  it  must  then  appear  that 
conditions  should  permit  successful  salvo  hring.  Different 
parts  of  a  long  target  may  be  taken  as  points  of  impact  for 
tlie  different  vessels  that  are  concentrating  thereon.  The 
pi-inciples  and  plan  to  be  followed  when  concentration  is  to  be 
employed  should  be  thoroughly  understood  and  form  a  well- 
understood  part  of  the  battle  plan,  and  not  left  to  be  com- 
pleted after  the  battle  has  been  begun. 

151.  Difficulties  of  collective  fire. — In  all  collective  fire, 
whetlier  for  one  or  several  ships,  the  interference  of  smoke, 
blast,  and  the  splash  and  explosion  of  shell  may  be  expected. 
With  fleets  or  divisions  the  difiiculties  incidental  to  maneuver- 
ing may  also  be  experienced.  These  may  all  be  overcome  by 
earnest  effort  and  thorough  preparation.  It  must  be  remem- 
bered that  all  the  difficulties  confronting  us  are  also  presented 
to  our  adversary,  and  the  men  and  the  fleet  that  have  best 
trained  for  and  anticipated  the  contingencies  of  battle  will  be 
the  least  disturbed  thereby. 

152.  Division  practice. — The  training  of  the  collective  fire 
of  several  ships  is  tested  in  the  various  forms  of  division 
pi-actice  that  are  prescribed.  Effort  is  made  to  make  these 
practices  realistic,  and  they  are  varied  from  year  to  year  in 
order  to  cover  different  phases  and  conditions.  The  weight 
given  these  forms  of  practice  in  the  competition  is  low  because 
of  the  difficulty  of  getting  the  exact  scores  of  individual  ships. 
It  nuist  n(»t  l)e  assumed,  however,  that  the  weights  assigned 
determine  the  importance  of  these  exercises,  in  which  to  some 
degree  competition  has  been  sacrificed  to  realism.  These 
exercises  are  iierhaps  the  most  important  of  the  year  as  tests 
of  the  training  of  the  battleships  for  war. 

153.  Battle  Signal  Book. — Attention  is  invited  to  the  "  De- 
velopment of  gunfire  "  given  in  the  Battle  Signal  Book,  1913. 


CHAPTER  7. 
TORPEDO  DEFENSE. 

154.  Character  of  problem. — The  problem  of  protecting 
capital  ships  aj^aiust  the  attack  of  torpedo  vessels,  under  the 
various  <'onditions  which  may  be  expected  in  war,  is  difficult 
and  is  one  now  giving  all  navies  much  concern. 

155.  Examples  during'  Russian  Japanese  War. — During 
the  recent  struggle  hetween  .lapan  and  Russia  several  of  such 
attacks  occurred  and  while  widely  different  I'esults  may  be 
expected  in  the  future,  as  a  result  of  better  training  and  ma- 
terial, the  following  figures  are  illuminating  when  considered 
in  connection  with  the  character  of  the  personnel  and  the 
(.■t)nditions  obtaining  in  the  two  navies  then  engaged  in  war. 

156.  First  case — Attack  on  ships  at  anchor  at  night  (Feb- 
ruary 8,  1904). — Ten  boats  attacked  eight  ships  anchored  off 
Tort  Arthur.  Attack  was  not  anticipated.  Nets  were  not 
rigged  and  preparations  to  defeat  an  attack  were  not  in  any 
sense  adequate.  Eighteen  torpedoes  were  fired,  and  three  hits 
were  made  on  Tsesarevitch,  Rctvizan,  and  Palluda.  The  Rus- 
sian gunfire  was  ineffective.  No  Japanese  torpedo  vessels 
were  struck. 

157.  Second  case — Attack  on  ships  at  anchor  at  night 
(June  23,  1904).— Fourteen  destroyers  and  sixteen  torpedo 
i)oats  attacked  ten  ships  anchored  off  Port  Arthur.  Nets  were 
rigged  and  the  attack  was  expected.  About  60  torpedoes  were 
fired  and  no  hits  were  made.  One  destroyer  and  three  torpedo 
boats  were  hit,   and  three  men  killed   and   five  wounded  by 

gunfire. 

55 


66  GUNNERY  INSTRUCTIONS. 

158.  Third  case — Attack  on  ships  under  way  at  night 
(August  10,  1904). — After  scattering  of  Russian  force  in  the 
battle  of  this  date,  tliree  Russian  ships,  the  Probeyda,  Sevas- 
topol, and  Fresvyct,  all  of  which  had  been  badly  used  in  day 
action,  were  attacked  by  17  destroyers  and  21  torpedo  boats. 
I'robably  about  70  torpedoes  were  fired.  No  Russian  ships 
were  hit.  Loss  admitted  by  Japanese,  nine  killed  on  one 
destroyer  that  had  been  hit  by  two  shells.  One  Japanese  de- 
stroyer struck  by  a  torpedo,  losing  one  killed  and  eiglit 
wounded.     This  vessel  was  not  sunk. 

159.  Figures  approximate. — The  above  figures  are  given  by 
a  prominent  British  naval  officer  and  writer,  but  may  be  only 
approximate.  They  indicate,  however,  that  the  difficulties  in- 
cidental to  torpedo  attack  at  night  are  by  no  means  confined 
to  the  battleship.  In  studying  the  question  the  point  of 
view  of  the  officer  of  the  torpedo  vessel,  and  of -the  submarine, 
and  of  the  difficulties  to  be  encountered  by  them,  must  be 
considered.  It  may  have  been  true  to  some  degree  that,  in 
the  cases  cited,  the  shots  that  did  not  liit  the  torpedo  craft, 
but  came  close,  may  have  counted  for  the  purposes  of  torpedo 
defense. 

160.  Rapidity  and  volume  of  fire. — In  repelling  an  attack, 
full  advantage  should  be  taken  of  the  rapidity  and  volume  of 
fire  permitted  by  the  type  of  gun,  the  number  of  guns,  and 
tlie  ammunition  supply,  provided  for  the  purpose.  Casualties 
to  material  of  course  must  be  anticipated. 

161.  Identical  methods  impracticable  in  all  ships. — Iden- 
tical methods  will  probably  not  be  equally  effective  in  all  of 
the  various  types  of  vessels  composing  the  fleet.  Zone  fire, 
which  lias  been  recommended  many  times  for  torpedo  de- 
fense, has  not  yet  been  given  a  practical  test.  The  training 
should  be  with  the  idea  of  using  to  a  maximum  the  battery 
and  facilities  for  control,  but  the  fact  that  the  peace  arrange- 
ments will  be  deranged  and  modifications  of  a  necessity  be 
introduced  in  service,  should  not  be  overlooked. 


GUNNERY  INSTRUCTIONS.  67 

162.  Artificiality  of  practices.— All  torpedo  defense  exer- 
cises must  be  to  a  considerable  degree  artificial,  but  in  no 
form  of  exercise  is  it  more  necessary  to  avoid  the  false  train- 
ing and  artificialities  practicable  in  peace  and  leading  to  in- 
correct deductions  and  plans  for  war,  than  in  torpedo  defense. 

163.  Concealment  and  searchlights. — p]ssentials  for  a  bat- 
tleship are  concealment,  evasion,  and  change  of  course  if 
there  is  likelihood  of  discovery.  The  occasion  may  arise, 
however,  when  searchlights  will  be  required.  Spotters, 
searchlight-control  men,  and  pointers  in  such  cases  must  all 
see  the  target.  Noises  and  confusion  must  be  absolutely  elimi- 
nated. The  beams  of  searchlights  must  be  handled  intelli- 
gently or  more  harm  than  good  will  result  from  their  use. 

164.  Necessity  for  a  program. — As  in  all  other  exercises,  a 
definite,  well-understood  program  is  a  first  and  last  essential 
to  success.  Attention  is  invited  to  the  type  plan  for  torpedo 
defense,  chapter  18. 


CHAPTER  8. 
TORPEDO  TRAINING. 

165.  The  end  in  view. — The  pnipose  of  all  torpedo  training 
i.s  the  efficiency  of  the  lorpedo  buttery  on  the  eve  of  war. 

This  includes  personnel  and  material,  and  may  be  otherwise 
stated  as  the  problem  of  getting  our  torpedoes  in  contact  with 
the  enemy  in  the  most  effective  way  and  under  the  peculiar 
conditions  to  be  anticipated  in  war.  Everything  that  is  done 
in  peace,  e\ery  daily  task,  small  or  large,  should  be  subjected 
to  this  criterion.  No  matter  how  convenient  or  expeditious 
proposed  methods  may  appear,  they  should  be  subordinated 
to  the  end  in  view. 

166.  Knowledge  of  material. — One  of  the  greatest  deter- 
rents to  progress  is  a  tendency  on  the  part  of  personnel  to 
simply  follow  general  directions  and  to  investigate  only  where 
troubles  have  forced  investigations.  Results  obtained  will 
lead  to  misdirected  effort  and  erroneous  conclusions  when  the 
users  of  material  fail  to  equip  themselves  with  detailed  and 
thorough  knowledge  of  the  mechanisms  with  which  they  work. 
The  starting  point,  therefore,  on  the  part  of  officers  is  a 
thorough  study  and  understanding  of  all  the  details  of  tlie 
mechanisms  assigned  to  their  charge.  Through  them  the 
necessary  knowledge  must  reach  the  enlisted  personnel.  It 
is  important  that  no  attempt  should  be  made  to  get  re.sults 
until  this  knowledge  is  first  obtained. 

167.  Damage  the  result  of  inexperience. — The  permanent 
damage  done   in  a   single  day   of  experimentation  by  Inex- 

58 


GUNNERY  INSTRUCTIONS.  69 

perienced  personnel  has  frequently  exceeded  that  which,  with 
proper  care,  should  be  expected  during  the  entire  normal  life 
of  the  material. 

168.  Full  advantage  taken  of  opportunities. — The  time 
which  vessels  can  devote  to  torpedo  tiring  during  a  year  is 
limited,  therefore  full  advantage  should  be  taken  of  all  op- 
IHirtunities  which  are  offered  for  practical  instruction  and 
exercise. 

169.  Coordination. — Successful  operation  of  torpedoes  re- 
quires cooperation  and  coordination;  in  other  words,  "team 
work  "  developed  to  a  high  degree  of  perfection.  It  is  abso- 
lutely essential  that  every  menil)er  concerned  in  the  prepara- 
tion of  a  torpedo  and  tube  for  firing  should  have  a  good  under- 
standing of  the  duties  of  every  other  man,  and  that  the  neces- 
sary work  involved  shall  be  so  systematized  and  organized 
that  nothing  will  be  left  to  chance.  A  single  detail  overlooked 
can  easily  ruin  a  performance  or  prove  disastrous.  Perma- 
nence In  stations  is  desirable. 

170.  Instruction. — Tiie  instruction  of  the  personnel  should 
commence  as  soon  as  the  tentative  assignments  to  stations 
have  been  made.  Due  to  the  lack  of  permanence  in  our  en- 
listed personnel,  a  constant  school  of  Instruction  on  board 
ship  must  of  necessity  be  maintained.  Courses  of  instruction 
should  be  laid  out  in  detail  in  advance  and  executed  as 
planned.  After  a  reasonable  time  has  been  devoted  to  the  in- 
struction, rigid  and  practical  examinations  of  each  man  on 
subjects  pertaining  to  his  station  should  be  conducted. 

171.  Sources  of  knowledge. — Stated  in  order  of  importance 
the  following  are  available  on  all  vessels  for  the  acquirement 
of  a  knowledge  of  torpedoes : 

(a)  Periodic  publications  of  the  department,  viz,  pamphlets, 
bulletins,  correspondence,  target  practice  reports. 

(b)  Working  drawings  and  descriptions. 

(c)  The  material  itself. 


60  GUNNERY  INSTRUCTIONS. 

Some  one  must  be  responsible  for  the  fact  that  a  complete 
set  of  publications  and  working  drawings  are  kept  on  hand, 
corrected  to  date  and  available  for  use.  Too  often  this  ques- 
tion is  left  to  care  for  itself,  and  nothing  is  done  until  delays 
or  troubles  develop  some  specific  detail  which  has  been 
neglected. 

172.  Nomenclature  and  methods  to  be  observed.^ — -A  strict 
adlierence  to  the  nomenclature  and  terms  used  in  the  instruc- 
tions, blue  prints,  pamphlets,  etc.,  must  be  observed.  The  use 
of  any  names,  terms,  etc.,  other  than  those  authorized  are 
indicative  of  carelessness,  and  results  in  confusion  and  loss  of 
time  both  on  board  ship  and  in  official  correspondence.  The 
methods  approved  by  proper  authorities  must  be  followed 
until  modified  or  revoked. 

173.  Routines. — The  following  tentative  routine  for  the 
crew  of  a  battleship  torpedo  room  is  outlined  as  a  guide : 

DAILY. 

Tiibes  :  /.  Unseat  sluice-gate  valves.    Just  start  off  seat  and 
close  again  quickly.     Drain  into  bilges. 

2.  Open  tube  covers  wide. 

3.  Sluice-gate  valve  must  be  closed,  and  the  tube 

cover   closed   and   locked   before   knocking   off 
work  and  report  made  to  torpedo  officer.     One 
of  the  chief  gunner's  mates  must  be  present 
when  this  is  done. 
(Note. — With  the  exception  of  the  opening  called  for  in 
liar.  1  above,  the  gate  must  always  be  kept  closed  and  locked, 
and  must  never  be  unlocked  without  permission  of  the  tor- 
pedo officer.) 

Torpedoes:  1.  Keep  all  oil  cups  full  at  all  times. 

2.  Turn  over  each  torpedo  by  hand  at  least  six 

revolutions. 

3.  Move   vertical   and   horizontal   rudders   full 

throw  at  least  six  times. 


GUNNERY  INSTRUCTIONS  61 

WEEKLY. 

Tubes :  1.  Run  out  spoi>ii  slowly  twice  Mondays  and  Thurs- 
days, uiiloss  other  work  prevents,  and  if  so  on 
lit  her  days,  torpedo  oflicer  to  be  jireseut. 
2.  Thursdays,  test  out  tiring  circuit  and  systems  of 
connnunication  from  conning  tower. 
Compressors,  Thursdays,  turn  over  and  run  against  a  load, 
unless  compressors  have  l)een  running  during  the  week. 

MONTHLY. 

Tubes:    /.    («)r  after  each   practice.)      Remove  toggle  gear. 
Clean  and  oil  with  sperm  oil,  neve.i'  with  vase- 
line or  thick  oil. 
Tori>edoes  :    /.  Each  torpedo  to  be  run   in  aii'  slowly  for  at 
least  five  minutes.     All  oil  cups  full. 
,1.   (Or  after  each   practice.)      Remove  and   in- 
spect gyro  mechanism,  and  oil  gear  train 
through  gyro  door.     Inspect  gyros. 
The  above   indicates  some  of  the  points  a   routine  sliould 
covcir. 

It  is  important  to  eliminate  everything  wliich  is  not  to  be 
carried  out  strictly  in  accordance  with  the  letter  of  the  rou- 
tine. The  routine  should  be  as  brief  and  concise  as  possible 
and  wi-itten  in  language  wliich  can  not  be  misconstrued. 

174.  Torpedo  officer's  notebook. — It  is  important  for  the 
torptMlo  ollicer  to  keep  a  notebook,  not  only  for  his  own  in- 
formation, but  for  that  of  his  relief.  The  foil  wing  are  sub- 
jects which  should  be  covered  in  such  a  notebook: 
All  orders,  bills,  instructions,  etc.,  issued. 
Notes  regarding  pernuinent  installations,  such  as  tubes,  air 
lines,  accumulators,  director  and  stand,  etc. 

Lists  of  repairs  and  alterations  recommended  for  navy-yard 
overhaul  period  with  action  taken  thereon. 


62  GUNNERY  INSTRUCTIONS. 

Collatiou  oi"  causes  of  any  abnormal  torpedo  performance, 
ami  measures  taken  or  suggested  to  remedy  same. 

All  data,  correspondence  or  computations  in  connection  with 
torpedo  tlepartment  whicli  may  be  of  future  value,  and  there- 
by save  duplication  of  work. 

All  notes,  opinions  or  conclusions  from  work  or  practice 
which  nnght  prove  of  value  for  future  work. 

175.  Importance  of  records. — The  importance  of  accurately 
and  completely  recording  all  available  data  and  carefully 
collating  san\e  for  every  shot  tired  can  not  be  overestimated. 
Tills  especially  applies  to  torpedo  work  on  a  battleship,  where 
at  best  l)nt  little  torpedo  practice  can  be  expected. 

176.  Torpedo  record  books. — These  should  be  kept  carefully 
and  accurately  and  shoidd  furnish  a  complete  history  of  each 
torpedo.  They  are  the  "  service  records "  of  the  torpedoes 
and  acc<Mnpany  them  throughout  their  existence.  It  is  im- 
portant to  keep  these  books  from  deterioration,  and  it  is  not 
advisable  to  use  them  habitually  in  the  torpedo  room  or  on 
deck,  but  to  treat  them  as  the  torpedo's  smooth  log,  writing 
them  up  after  a  day's  tiring  or  practice. 

177.  Rough  log. — A  rough  log  should  be  kept  which  em- 
bodies all  necessary  information.  It  Is  unnecessary  to  repeat 
in  tills  log  adjustments  which  are  permanent,  but  there  is 
much  information  peculiar  to  the  ship  or  worlv  wliich  does 
not  find  a  place  in  the  record  books,  but  which  is  important 
and  which  should  be  entered  herein.  An  excellent  method  is 
the  adoption  of  a  large  loose-leaf  rough  log  with  .separate 
sheets  for  each  torpedo.  Boards,  one  for  eacli  torpedo,  should 
be  conveniently  hung  in  the  torpedo  room  and  before  each 
day's  practice;  it  should  Ix^  tlie  duty  of  one  of  the  crew  to  get 
the  sheets  of  the  torpedoes  to  he  fired  and  attach  them  to  the 
proiter  boards.  It  is  important  that  all  entries  should  be  made 
immediately  after  the  data  are  obtained.  The  system  should 
be  systematically  carried  out;  entries  should  not  be  left  to 
nieniory.  or  incompleteness  tolerated. 


GUNNERY  INSTRUCTIONS.  68 

178.  Entries  in  rough  log. — The  following  covers  the  most 
important  entries  required  for  the  roufih  log: 

TORPEDO   ROOJiI    DATA. 

Date. 

Shot  No.  for  (My. 

Serial  shot  No.  for  torpedo. 

Torpedo  No. 

Tube. 

Predicted  .speed. 

Kegulator. 

Initial  llask  pressure. 

I'"iiial  flask  pressure. 

Changes  of  ad.jiistnient  from  last  shot. 

Ifemarks. 

BRIDGE   DATA. 

Course  oC  firing. 
Director  set. 

Was  shij)  swinging,  and  which  way? 

Average  I'evolutions  per  minute.  ,1  minutes  before  tiring. 
Speed  of  ship  at  instant  of  firing  torpedo. 
Does  engine  room  report  .speed  was  over  or  under  standard 
revolutions  per  minute  wheH  sliot  was  fired? 
Current,  direction  of  set. 
.\niount  in  4  minutes  (feet). 
Observations  and  remarks  on  run  as  seen  from  bridge. 

KEPORTED   FROM   RANGE. 

Time  run  for  2.000  yards. 

Time  run  for  3,000  yards. 

Time  run  to  target. 

Natural  deflection. 

Depth  at  target. 

"Total  distance  ran   (important). 

Remarks. 

Sketch  of  run  as  observed  at  target. 


64  GUNNERY  INSTRUCTIONS. 

REMARKS   AFTER  RECOVERY  OF  TORPEDO. 

Correct  speed  of  torpedo. 
Correct  deflection  of  torpedo. 
Director  correction  for  next  stiot. 

179.  Responsibility  for  results. — Whether  there  he  hits, 
misses,  accidents,  or  losses,  rests  solely  with  the  ship's  force 
and  can  not  be  delegated.  Torpedoes  should  not  be  fired  nor 
should  any  tests  be  carried  out  unless  the  equipment  is  in 
proper  condition  and  all  necessary  data  can  be  collected. 

180.  Assembling  and  disassembling  of  torpedoes. — .Vs  a 
general  rule,  torpedoes  should  not  be  disassembled  except  for 
very  good  reasons,  such  as  failures  in  tests,  runs,  or  for  peri- 
odic overhauls  for  purixtses  of  renewing  washers,  gaskets, 
cleaning,  examination,  or  for  instruction  purposes.  The  cause 
of  every  erratic  performance  should,  however,  always  be  defi- 
nitely determined.  On  first  receipt  of  a  torpedo  on  board,  it 
should  be  entirely  disassembled,  overhauled,  and  the  fact  of  its 
lieing  in  projier  condition  verified  to  the  satisfaction  of  the 
ship's  personnel.  The  fact  that  the  torpedo  may  or  should 
have  been  in  proper  condition  before  issue  does  not  relieve  the 
personnel  afloat  of  any  responsibility  whatever.  Unsatisfac- 
tory conditions  discovered  on  overhaul  after  issue  should  be 
reported  to  the  department  as  a  matter  of  information. 

181.  Handling  torpedoes. — A  template  of  a  torpedo  should 
be  made  in  a  new  .ship,  and  a  satisfactory  method  of  handling 
should  be  developed.  The  leads  of  purchases,  positions  of 
booms  and  davits  with  respect  to  the  vessel's  side,  and  tor- 
pedo trunks,  obstructions,  torpedo  rooms,  etc.,  should  be  care- 
fully noted.  It  will  i-equire  considerable  practice  before  tor- 
pedoes can  be  handled  quickly  and  with  safety. 

182.  Precautions  before  firing  torpedoes. — All  necessary 
adjustments,  precautions,  and  tests  before  firing  torpedoes 
are  completely  set  forth  in  publications  of  the  department. 


GTTNNERY  rNSTRUCTIOWS.  65 

The   following   two   causes   of   losing   torpedoes   are   directly 
chargeable  to  personnel : 

(1)  Sinking  due  to  failure  of  the  torpedo  to  start. 

(2)  Sinking  at  end  of  run  due  to  leaks  in  afterbody  or 
immersion  chamber. 

These  are  preventable  faults.  Tube-firing  mechanisms  can 
be  verified  without  firing  a  torpedo.  Care  must  be  exercised 
not  to  alter  the  weight  disposition  of  torpedoes,  particularly  as 
regards  uprightness. 

183.  Erratic  depth  and  deflection. — Two  causes  of  erratic 
depth  and  deflection  which  are  difficult  to  detect  aboard  ship, 
and  which  are  frequently  ascribed  to  other  causes  with  much 
consequent  misdirected  effort,  are  as  follows: 

(1)  Fluctuations  in  speed. 

(2)  Torpedo  not  upright  due  to  alteration  of  weights,  pro- 
pellers unbalanced,  or  unbalanced  friction  in  propelling  mech- 
anism. 

184.  Rapidity  of  fire. — A  certain  degree  of  proficiency  can 
be  attained  by  simulating  all  the  conditions  of  loading  ex- 
cept that  of  actually  using  the  torpedoes,  but  it  is  necessary 
to  employ  the  torpedoes  to  complete  this  instruction.  Load- 
ing drill  with  torpedoes  is  just  as  essential  as  turret  loading 
drill,  and.  if  properly  carried  on,  can  be  made  to  simulate  real 
loading  to  perhaps  a  greater  degree  than  does  turret  drill 
After  the  crew  becomes  proficient  in  loading  the  torpedo  into 
the  tube,  the  start  can  be  made  with  the  tube  flooded  as  if  a 
torpedo  had  just  been  fired.  During  this  drill  the  torpedo 
officer  should  always  be  required  to  set  gyro  angles  by  means 
of  the  outside  device,  to  test  the  device,  and  to  render  him- 
self proficient  and  rapid  in  this  most  important  duty.  The 
gyro  angle  after  being  set  should  invariably  be  checked  up  by 
a  second  person. 

Rapidity  of  loading  torpedoes  into  submerged  tubes  (assum- 
ing the  torpedoes  to  be  fully  charged  and  completely  ad- 
34770—18 5 


66  GITNNERY  rNSTRTICTIONS. 

justed,  with  the  gyro  iudex  set  at  0)  depends  upon  (1)  the 
easy  and  proper  functioning  of  the  tube  and  all  its  parts, 
(2)  the  use  of  necessary  and  efficient  means  for  actually 
handling  the  torpedoes,  and  (3)  the  manual  dexterity  and 
proper  coordination  of  the  work  of  the  crew. 

In  rapid  firing  one  torpedo  will  be  in  the  tube  and  ready, 
the  second  (charged  and  adjusted  for  run)  held  in  the  load- 
ing position  above  the  tube  by  half  strap,  and  the  other  tor- 
pedoes resting  (charged  and  adjusted)  in  chocks  near  tube. 
Upon  firing  the  first  torpedo,  the  tube  will  be  blown,  cover 
opened,  and  second  torpedo  loaded  as  rapidly  as  possible. 
The  third  should  be  placed  in  loading  position,  over  cover, 
as  soon  as  second  torpedo  is  loaded,  and  the  fourth  and  suc- 
ceeding torpedoes  moved  into  more  convenient  locations. 

185.  Procedure  for  angle  fire  using  outside  gyro  set- 
ting.— Required  angle  "10  right  (left),"  etc.;  transmitted 
over  voice  tubes  from  the  directing  station. 

After  the  discharge  of  a  torpedo.  No.  1  (see  sketch)  bring 
spoon  back  to  battery,  using  hand  gear  if  necessary. 

Torpedo  officer  sees  spoon  toggled,  and  commands  "  Load." 

No.  3  draws  back  firing  rod. 

No.  4  reverses  bolt,  and  closes  gate  while  No.  1  blows  down. 

The  instant  the  gate  is  closed,  No.  5  opens  tube  cover, 
assisted  by  No,  4. 

(Do  not  wait  to  drain  tube;  time  will  be  lost,  and  a  few 
gallons  of  water  on  the  deck  can  do  no  harm.) 

Nos.  2.  5,  and  6  load  torpedo  on  tube  cover;  No.  2  removes 
propeller  lock  and  reports  having  done  so  to  torpedo  officer; 
No.  5  closes  tube  assisted  by  No.  4. 

Torpedo    officer    commands     (1)    "Flood   tube,"    and    (2) 

"Charge  with  lbs."     (The  latter  is  the  command  to  No. 

1  to  charge  the  air  reservoir  for  firing.) 

No.  2  operates  the  air  release  valve  while  the  tube  is  being 
flooded. 


GTIinJEEY  INSTE1JCTI0NS. 


67 


Gdle  Operdling 
Gear 


Torpedo    Officer 
Stalloned  Here 


Sketch  showing  stations  for  loading  submerged  torpedo  tubes. 


68  GTJNITEEY  HTSTTHTCTIOITS. 

No.  0  meshes  the  curve  fii'e  spindle. 

The  torpedo  officer  reports  "  Ready  for  angle  "  to  the  direct- 
ing station. 

The  angle  is  obtained  and  set  as  before,  and  the  instant  the 
tube  is  flooded  the  torpedo  officer  reports  "  Ready." 

Upon  "  Stand  by  "  from  the  directing  station  the  curve  fire 
spindle  is  withdrawn. 

186.  Care  of  the  outside  gyro-setting  device. — As  the  out- 
side gyro-setting  mechanism  is  somewhat  frail,  care  must  be 
exercised  with  it,  as  there  is  some  danger  of  brealiing  or 
twisting  the  shaft  extension.  This  device  should  be  tested, 
turned  daily,  and  freely  oiled.  An  important  feature  of  easy 
and  accurate  angle  setting  is  the  freedom  of  the  angle  mecha- 
nism in  the  afterbody  and  in  the  gj'ro  gear,  and  the  proper 
amount  of  friction  between  the  cam  plate  and  outer  gimbal 
ring  of  gyro.  The  cam  plate  and  its  seat  on  outer  gimbal  ring 
should  be  both  perfectly  clean  and  free  from  verdigris  or  any 
matter  w'hich  would  increase  friction ;  the  proper  degree  of 
friction  is  provided  for  by  design  of  the  cam  plate  friction 
ring. 

187.  To  use  outside  g'yro-setting  device. — Before  attempt- 
ing to  use  the  outside  gj-ro-setting  gear  be  sui-e  that  (1)  the 
cam  plate  is  not  binding  on  gimbal  ring  (the  normal  spring 
tension  holds  cam  plate  rather  stiffly  to  the  ring)  ;  (2)  that 
angle  gear  in  gyro  housing  in  afterbody  of  torpedo  works 
freely  (this  gearing  frequently  gets  very  stiff  after  a  long 
period  of  disuse)  ;  (3)  that  angle-setting  device  is  operating 
freely;  and  (4)  that  the  pointer  on  dial  of  outside  setting 
device  (outside  of  torpedo)  is  pointed  exactly  abeam,  thaf  is, 
on  90°  for  starboard  tubes  and  270°  for  port  tubes,  the  dials 
being  graduated  from  0  at  head  to  the  right. 

When  putting  a  gyro  in  a  tube  be  sure  that  the  pointer  on 
outer  gimbal  ring  exactly  coincides  with  the  zero  mark  or 
cam  plate,  and  that  the  gyro  index  on  shell  of  torpedo  reads 


GUIOIERY  DTSTRTJCTIONS.  '  6» 

zero  when  {rfmbal  is  placed  in  houslnj?,  and  that  the  outside 
angle-setting  dovice  reads  zero. 

188.  To  engage  outside  setting  device. — When  torpedo  is 
in  tulie  and  cover  locked  to  engage  the  outside  augle  setting 
gear  for  a  curved  run,  release  shaft  lock  and  press  shatt  in  to 
within  about  half  an  inch  of  the  home  position;  continue  the 
pressure,  turning  slightly  right  then  left,  and  feeling  for  the 
engagement  of  shank  of  shaft  extension  with  socket  in  tor- 
pedo. When  accomplished  this  engagement  can  be  distinctlj' 
felt;  push  shaft  all  the  way  home  and  lock  (press  down  small 
lever  under  dial).  Turn  handle  as  required  to  set  torpedo  for 
angle  run  with  all  gearing  engaged.  The  outside  handle  will 
turn  rather  stiffly,  and  care  must  be  taken  not  to  twist  too 
hard  or  suddenly.  To  eliminate  any  possible  lost  motion  in 
gearing,  note  reading  of  large  scale  on  handle  when  cam  plate 
starts  turning;  then  always  turn  handle  in  same  direction  and 
use  the  initial  I'eading  as  the  zero  point. 

When  angle  is  properly  set,  withdraw  shaft  firing,  raising 
small  lever  underneath  to  release  same.  It  will  be-  noted  that 
the  shaft  can  not  be  turned  as  long  as  the  small  locking  lever 
is  in  the  upward  position.  This  is  to  insure  exactly  the  same 
engagement  as  before  the  shaft  was  withdrawn,  in  case  it 
should  become  necessary  to  reengage  and  reset  angle.  So  long 
as  a  torpedo  is  in  tube  and  the  gyro  setting  shaft  withdrawri, 
the  lever  should  be  kept  in  the  upward  position. 

189.  Precautions  to  be  observed  in  handling  charged  tor- 
pedoes.— Certain  precautions  should  be  observed  in  rapid  han- 
dling of  charged  and  ad.lusted  torpedoes.  Remember  that  the 
stop  valve  is  wide  open ;  after  filling  fuel  flask,  the  torpedo 
should  be  kept  upright  until  ready  for  loading  in  order  to  pre- 
vent a  possible  loss  of  fuel  through  check  valve.  The  starting 
lever  nuist  be  guarded  with  the  greatest  care.  To  prevent 
tripping  the  starting  lever  some  ships  use  a  small  wooden 
wedge  pressed  into  the  recess  behind  the  starting  lever,  and 
connected  by  a  lanyard  to  the  propeller  lock.    By  this  means 


70  GUNNERY  INSTRUCTIONS. 

both  wedge  and  lock  are  reasonably  certain  to  be  removed 
when  torpedo  is  loaded,  and  the  torpedo  is  "locked"  as  long 
as  the  wedge  is  in  place. 

190.  Accuracy  of  fire. — This  depends  on  an  accurate  deter- 
mination of  the  course,  speed,  and  range  of  the  enemy,  as  well 
as  on  the  adjustment  of  the  torpedoes. 

191.  Importance  of  correct  directing. — Those  who  in  battle 
would  be  charged  with  the  directing  of  torpedoes  must  ap- 
preciate the  importance  of  their  duties  and  frequent  exercise 
should  be  given  them.  The  system  of  communication  between 
the  director  stations  and  the  torpedo  rooms  must  be  efficient 
and  the  methods  for  outside  gyro  setting  and  the  various 
operations  incidental  to  the  firing  of  torpedoes  must  all  be 
thoroughly  prepared  for  by  exercise  and  drill. 

192.  Directing. — The  general  problem  of  directing  can 
easily  be  mastered.  The  possibility  of  torpedoes  being  used 
suddenly  and  without  much  warning,  when  guns  are  or  are 
not  being  used,  and  of  director  stations  being  wrecked  must 
be  provided,  for.  Each  torpedo  must  be  directed  according  to 
its  own  previous  performance  in  accordance  with  data  ob- 
tained on  proving  practice.  Torpedo  tubes  should  be  "bore- 
sighted"  for  alignment  of  directors  periodically. 

The  following  are  some  of  the  points  which  must  be  taken 
into  consideration  in  procuring  the  data  for  directing  setting: 

(a)  If  a  gyro  gear  has  been  under  adjustment,  or  a  gyro 
mechanism  removed  and  replaced,  the  deflection  may  be  differ- 
ent from  that  of  a  previous  shot,  although  the  gyro  is  supposed 
to  be  in  satisfactory  adjustment. 

(b)  Speeds  are  not  uniform  throughout  a  run,  nor  are  they 
exactly  uniform  for  successive  runs  of  the  same  torpedo. 

(c)  Firing  interval  may  vary. 

(d)  Swinging  of  ship  during  firing  interval. 

(e)  Unintentionally  firing  early  or  late. 
(/)   Variations  in  speed  of  ship. 

(i/)  Variations  in  speed  of  expulsion. 


GimNERY  INSTRUCTIONS.  71 

(ft)  Instrumental  error  of  director  clue  to  lost  motion, 
springius  of  telescope  mounting,  and  various  kindred  errors 
due  to  design  and  mounting  of  instrument. 

193.  Requirements  for  directing-. — Some  of  tlie  require- 
ments for  directing  torpedoes  are  as  follows : 

(1)  Station  near  as  possible  over  the  tube. 

(2)  Clear  of  gun  blast  and  a  clear  arc  of  vision  well  aft. 

(3)  Behind  armor. 

(4)  Efficient  comnmnication  direct  to  tubes. 

(5)  Satisfactory  range-finder  arrangements. 

(6)  Satisfactory  arrangements  for  obtaining  course  and 
speed  of  enemy. 

(7)  Communication  with  captain  and  fire-control  officer. 
Angles  may  be  transmitted  from  the  director  station  for 
curved  fire  to  the  torpedo  tubes  by  means  of  the  electric  trans- 
mitters, one  for  each  tube.  Turning  a  handle  lights  up  the 
desired  angle  reading,  also  rings  a  bell  to  attract  attention. 
This  transmitter  in  all  cases  has  not  given  satisfaction,  and 
the  voice  tube  or  telephone  are  generally  used  for  this  purpose. 

194.  Kinds  of  torpedo  practice. — There  are  two  forms  of 
practice  with  torpedoes  necessary  in  preparation  for  target 
pi-actice.  They  may  be  termed  "  Test  practice  "  and  "  Proving 
practice."  Torpedoes  should  not  be  fired  on  target  practice 
until  these  have  been  conducted. 

195.  Test  practice. — Tliis  is  held  with  reduced  air  pressure. 
Positive  buoyancy  of  the  torpedo  should  be  insured. 

Results  obtained  from  Test  practice: 
(a)  Test  of  tubes. 

{b)  Elementary  lest  of  torpedoes  after  their,  first  receipt 
aboard. 

(c)  Verification  of  adjustments,  etc. 

(1)  Following  extensive  overhauls. 

(2)  To  verify  stability. 

(3)  To  locate  puzzling  faults  by  process  of  elimination. 

196.  Proving  practice. — Torpedoes  firetl  with  full  air  pres- 
sure.   This  practice  is  analogous  to  a  calibration  practice  of 


72  GUNNERY  INSTRUCTIONS. 

guns,  and  should  be  carried  out  between  each  competition 
prescribed  by  the  department.  Its  object  is  to  obtain  reliable 
data  as  to  speed,  deflection,  and  depth  performances  ot  tor- 
pedoes. Under  no  circumstances  should  such  an  annual  prac- 
tice be  omitted.  Torpedoes  should  be  fired  under  similar  con- 
ditions successively  luitil  running  normally.  It  is  important 
that  each  overhaiding  for  the  elimination  of  faults  should 
be  followed  by  proving  practices  until  a  normal  performance 
is  obtained.  It  is  inadvisable  to  lay  aside  a  torpedo  which 
has  made  an  abnormal  run,  for  an  indefinite  period,  as  this 
is  discouraging  to  the  personnel  and  involves  a  waste  of  time 
and  energy.  Proving  practice  does  not  necessarily  mean  a 
continuous  running  of  torpedoes.  The  occasion  of  this  prac- 
tice is  the  best  for  overhauling  torpedoes,  and  a  great  part  of 
the  time  set  aside  will  be  consumed  in  overhauling. 

197.  Conditions  for  fixed  torpedo  rang'e. — Ideal  range  con- 
ditions would  be  as  follows : 

(a)  Not  less  than  1.5  fathoms  of  water  over  at  least  first 
half  of  range,  diminishing  thereafter  to  5  fathoms  at  end  of 
torpedoes"  runs. 

(b)  Comparatively  hard  bottom.     No  soft  mud. 

(c)  Clear  of  shipping. 

(d)  Calm  sea. 

198.  Current  observations. — Attention  must  be  given  on 
fixed  ranges  to  effects  of  tide  and  currents.  A  successful 
method  to  observe  current  is  as  follows : 

Take  observations  from  boats  at  target  and  at  firing  point 
innuediately  preceding  each  shot  as  follows : 

Gear :  Spar  weighted  to  float  vertically  with  ujiper  end  just 
at  surface,  and  mounted  with  a  small  flag. 

A  light  line  marked  as  lead  line,  or  in  feet,  and  secured  to 
upper  end  of  spar. 

A  good  compass. 

Stop  watch. 


GTTNNERY  INSTRTJCTIOUS.  78 

Procedure:  On  signal,  sufficiently  before  a  run,  release 
spar  from  alongside  of  boat  and  note  set  and  drift  in  the  time 
of  a  torpedo  run  to  target.  Signal  results  to  the  ship  for 
directcir  ndjustnieMits. 

199.  Loss  of  toi-pedoes. — If  test  practice  has  been  efficient 
and  the  personnel  is  reasonably  experienced,  greater  depths 
tliiui  20  fathoms  will  result  in  a  reduction  rather  than  an 
inci-case  of  torpedo  losses,  this  with  a  view  of  keeping  run- 
ning torpedoes  clear  of  the  bottom  regardless  of  their  depth 
performance.  The  torpedo  travels  in  arcs  of  circles  in  the 
vertical  as  well  as  in  the  horizontal  plane.  Very  few  torpedoes 
will  be  lost  if  the  following  conditions  are  fulfilled : 

(1)  Absolute  insurance  against  failure  of  propelling  mech- 
anism to  start. 

(2)  Absolute  insurance  against  shell  leaks  which  may  cause 
negative  buoyancy  after  run  and  before  recovery. 

(3)  Efficient  organization  of  the  observation  force  aboard 
ship  and  on  the  range. 

(4)  Practice  restricted  to  forenoons,  commencing  as  early 
as  possible.  Under  no  circumstances  ever  fire  later  than  four 
hours  before  sunset. 

300.  Proving  practice  under  way. — In  time  of  war  and 
under  certain  circumstances  "Proving  practice"  over  a 
measured  range  may  be  impossible. 

Under  such  circumstances  for  torpedo  .vessels,  one  such  form 
of  practice  would  be  as  follows:  Firing  vessel  and  observa- 
tion vessel  under  way,  but  stopped  and  distant  from  each 
other  the  desired  proving  range.  Angles,  range  finder  read- 
ings, and  reciprocal  bearings  taken  at  time  of  firing.  It  is 
important  that  vessels  should  not  move  through  the  water 
during  run  of  torpedo.  This  form  of  practice  may  also  be 
carried  out  by  battleships  using  light-draft  vessel  (tug  or 
destroyer)   as  target  and  observation  vessel. 

201.  Proving-  practice  without  a  regular  range. — Another 
form  for  battleships  at  anchor  in  open  roadsteads  or  harbors 


74  GTTNNERY  INSTRUCTIONS. 

where  conditions  prevent  laying  out  a  range  is  outlined  as 
follows : 

B — Battleship  at  anchor. 

(1)  Observation  party  at  boom. 

(2)  Mid-range  observation  party. 

(3)  Maximum-range  observation  party. 

(4)  Recovery  obsei'vation  party. 

(5)  Recovery  party. 

Observation  parties  should  be  equipped  with  signals,  stadi- 
meter,  binoculars,  nose  and  tail  lines,  stop-valve  tools,  and 
propeller  lock. 

When  ready  to  fire,  B  moves  (3)  by  signals  until  line  of  sight 
is  on  and  then  fires.  (2),  (4),  and  (5)  maneuver  to  keep  in 
position  on  B  and  (3).  Ou  B  firing,  (2)  and  (3)  take  dis- 
tance. (2)  and  (3)  must  not  move  through  water  during  run 
of  torpedo.  Have  observers  aloft  equipped  with  glasses. 
Boats  (1),  (2),  and  (3)  give  chase  as  soon  as  torpedo  passes; 
(4)  and  (5)  move  as  directed  by  ship  to  get  in  torpedo  path. 
All  boats  resume  station  as  soon  as  one  of  them  reports  by 
signal  that  torpedo  is  alongside. 

202.  Observation  parties. — Parties  composed  of  well- 
instructed  and  organized  observers  to  watch  the  run  of  torpe- 
does from  the  ship  and  from  range  boats  are'  essential  to 
efficient  development  and  are  also  necessary  to  insui'e  against 
torpedo  losses.  Mid-range  observers  should  always  be  used, 
and  should,  if  possible,  be  as  accurately  located  as  the  target. 
This  procedure  will  afford  valuable  information  which  can 
bo  obtained  in  no  other  way  concerning  speed,  deflection, 
heater  failures,  and  depth  performances.  A  boat  should  be 
kept  near  the  firing  point  for  observations  and  instant  use 
in  case  of  emergencies  in  that  neighborhood.  Careful  organi- 
zation beforehand  and  a  definite  common  understanding  be- 
tween torpedo  room,  bridge,  and  range  ax'e  absolute  essentials. 
It  should  be  an  established  rulCi  that  all  boats  should-  give 
chase  as  soon  as  a  torpedo  is  sighted.    Boats  must  never  as- 


GUNNERY  INSTRUCTIONS.  76 

sume  that  another  has  the  torpedo  in  sight  and  is  going  to 
get  it,  until  they  actually  see  a  boat  in  its  immediate  vicinity, 
and  talcing  hold.  Tliis  may  appear  to  be  an  unnecessary  pre- 
caution, but  experience  will  prove  otherwise.  It  is  very  easy 
to  lo.se  sight  of  a  lloating  torpedo  even  in  comparatively 
smooth  water. 

203.  Recovery  of  torpedoes. — Range  boats  should  be  sup- 
plied with  "nose  and  tail  lines"  and  marker  buoys.  Boats 
stationed  beyond  the  target  should  also  be  supplied  with  a 
stop-valve  tool  and  propeller  lock.  The  stop  valve  should  be 
closed  and  propeller  lock  put  on  at  the  end  of  a  run.  Nothing 
else  should  be  touched  in  order  that  all  possible  evidence  will 
be  available  for  diagnosis  on  receipt  aboard.  Diaguosis  is 
important  wliether  the  run  has  been  normal  or  otherwise. 
Horizontal  rudders,  starting  lever,  water  tripper,  etc.,  as  well 
as  any  foreign  material  which  may  be  foul  of  tail,  should 
not  be  touched  before  delivery  aboard.  It  is  important  in 
approaching  a  torpedo  or  handling  alongside  that  the  boat 
keep  clear  of  the  head,  immersion  chamber,  afterbody,  and 
tail.  The  air  flask  can  not  be  harmed,  but  the  other  parts  men- 
tioned are  easily  dented  or  damaged.  ,  The  great  cost  and 
military  value  of  the  torpedo  make  it  essential  that  evejry 
effort  be  made  to  recover  torpedoes.  If  an  erratic  run  has 
been  made  the  loss  of  the  torpedo  will  prevent  the  investiga- 
tion and  discoverj'  of  the  cause  of  the  faulty  performance. 
See  diagram  illustrating  arrangement  of  boats  for  recovery  of 
torpedoes. 

204.  Signals  and  diagrams.— (o)  Signals. — It  is  extremely 
difficult  for  observers  in  a  small  boat  2  miles  and  over  distant 
to  make  out  signals.  As  the  important  signals  required  for 
range  parties  are  few,  it  is  advisable  to  make  them  with  large 
flags.  Portable  radio  sets  in  steamers  have  been  found  most 
useful. 

Special  designating  signals  for  boats  on  torpedo  range 
should  be  arranged,  as  distinguishing  pennants  often  can  not 


76  GTniNERY  INSTRTTCTIONS. 

be  made  out  and  also  as  boats  can  better  be  designated  ac- 
cording to  their  assigned  stations  on  the  range  which  may 
change  according  to  locality  and  nature  of  the  practice. 

In  addition  to  the  General  Signal  Book,  the  following  code 
of  special  signals  have  been  found  useful  in  torpedo  practice, 
AVhen  it  is  desired  to  signal  to  any  boat  on  the  range,  the 
numeral  flag  of  the  position  she  is  then  occupying  will  be 
hoisted  over  the  signal  in  exactly  the  same  manner  as  that 
used  in  signaling  between  ships.  Similarly  groups  will  be 
called  by  hoisting  the  international  code  flag  of  group  desired. 
The  international  code  flag  F  will  be  hoisted  in  a  conspicuous 
place  on  a  separate  set  of  halliards  when  using  the  signal  of 
this  code. 
A 
B  Torpedo  sunk   (flown  in  bow  of  boat  standing  by  marker 

buoy). 
C  Code  flag. 

D  Hits — indicated  by  numerals  below. 
E  Half  hits — indicated  by  numerals  below. 
G  Torpedoes  all  recovered  (not  yet  hoisted  on  board). 
I  Torpedoes  in  sight  ^bearing  may  follow). 
K  Torpedo  sunk  alongside. 
O  Torpedo  sunk  (repeater  below  to  indicate  which  one;  first, 

second,  or  third). 
P  Torpedoes — all  hoisted  on  board — (numeral  below  to  indi- 
cate number). 
Q  Steam  to  right  (number  of  points  indicated  by  numerals  be- 
low). 
T  Torpedoes  in  tow. 
X   Steam  to  left    (number  of  points  indicated  by   numerals 

below). 
Y  Steam  away  from  ship. 
Z  Steam  toward  ship. 

AB  Torpedo  is  making  erratic  run   astern   this  or  ship  in- 
dicated. 


GUNNEEY  INSTIITICTIOB'S.  T7 

AC  Torpedo  is  ruaking  erratic  run  port  quarter  tliis  or  ship 
indicated, 

AD  Torpedo  is  making  erratic  run  port  beam  this  or  ship 
indicated. 

AE  Torpedo  is  making  erratic  run  port  bow  this  or  ship  in- 
dicated. 

AF  Torpedo  is  making  erratic  run  ahead. 

AS  Torpedo  is  luakiug  erratic  run  starboard  bow  this  or 
ship  indicated. 

AH  Torpedo  is  making  erratic  run  starboard  beam  this  or 
ship  indicated. 

AI  Torpedo  is  making  erratic  run  starboard  quarter  this  or 

ship  indicated. 

Note. — Signals  AB  to  AI  are  orders  for  boats  in  the  immediate 
vicinity  of  tbe  torpedo  to  proceed  to  the  spot  and  recover  the  torpedo 
when  it  stops  running  or  Imoy  the  spot  in  case  It  goes  down. 

A  J  Torpedo  (shot  indicated  by  numeral  below)  passed  ahead 
of  target. 

AK  Torpetlo  (shot  indicated  by  numeral  below)  passed  astern 
of  target. 

AL  Boat  or  group  indicated  follow  and  recover  torpedo  bear- 
ing from  boat  or  group  as  indicated  (distance  in  yards  may 
be  indicated). 

BF  Ahead. 

CE  Astern. 

DQ  Port  bow. 

EI  Port  beam. 

FA  Port  quarter. 

FL  Starboard  bow. 

RQ  Starboard  beam. 

SU  Starboard  quarter. 

UP   

VE    

YO   

ZI 


78 


GUWNEEY  rNSTETTCTIOUS. 


SHCTCH  -  DISroSITION  OF  BOATS  roR  TAHGET  PRACTICE 


Oroup  "A"-  Posrticns  Nos.  I,  Z,  dndi- 

Group  "R"-        "  Nos.  A.S.^r^dt. 

C-  roup  "C-  "  /ios.  7,  8,  dfld  9. 

Group  "D-  "  Nos.  10,11,  and  IZ 

Group  'A "  Bojis  from  Ihe 

Oroup"B" 

Qroup  'C "       •  .       . 

(  Boais  irom  the 

( In  dbssncc  of 
Group  'D'iOne  motor  sai/ing  Ldunch 

[from  edch  s/iip  of  t/ie 

{Firing  Division. 


/  Course  of  firing  S/iip  and  FcUomng  phip. 


Group  "D"      1 


:2s 


%-soo  -iMM  joo'^ir^" 


Group  "  D,"  Leader  3,800  yards  from  target. 

NOTK. — In  addition  to  tbe  arrangements  of  ships  sliown  In  sketch, 
one  ship  l^eeps  position  near  the  towing  ship,  either  ahead  or  astern, 
during  the  entire  practice. 


GimNEBY  INSTRUCTIONS. 


79 


205.  Deterioration  caused  by  salt  water. — It  is  harmful  to 
allow  toi-pedoes  to  remain  in  the  water,  as  water  getting  into 
the  g3'ro  pot,  afterbody,  immersion  chamber,  etc.,  causes  de- 


■< 


A  •  T^r^ert  SAi'p, 


—■  ZOO  •*- 

o — o — O— O r  — 

'245-     joo 

joo  A  I 

-* o- -o 600 

J  6  I 

7    T 

600 

I 

600 

I 


r 


.Jl__ 


10      II     IZ 


Group  "A"  Boats  I  ,Z,3, 
Group  B"  Boats  4:5,6, 
Group  "C"  Boats  ?,  a,  9, 

Group    "D"  Boats  10,  II,  IZ,   Motor  sailing  laurK/ie.3, 
From 


3500Yds 


Course  of  firing  Division.  ^ 


Disposition  of  boats  for  battle  practice. 


terioration.  Gyros  should  be  taken  out,  cleaned  and  oiled  as 
soon  as  possible  after  a  run  to  prevent  deterioration  of  the 
bearings. 


80  GITNNERY  INSTRTICTIONS. 

206.  Possibilities  of  actual  service. — In  developing  the  per- 
sonnel and  material  the  possibilities  of  actual  service  should 
never  be  lost  sight  of.  The  ability  to  maintain  gyros  and 
other  parts  in  adjustment,  and  to  keep  torpedoes  loaded  in  the 
tubes  and  ready  for  firing  for  long  periods  must  be  acquired. 
The  adjustment  of  the  war  nose  and  details  used  only  in  war, 
the  quick,  accurate  use  of  the  torpedo  under  all  of  the  peculiar 
conditions  and  emergencies  that  may  occur  in  actual  service 
must  be  anticipated  and  prepared  for.  Ability  to  recognize 
and  seize  opportunity  for  torpedo  firing  is  essential.  Training 
should  always  be  with  the  idea  that  the  torpedoes  may  be 
employed  while  the  guns  are  engaged.  A  full  knowledge  of 
the  favorable  positions  for  offense  and  defense  is  necessary. 
The  training  includes  the  tracking  of  the  enemy  (target)  i.  e., 
the  correct  estimation  of  his  course,  speed  and  range,  and 
formation,  as  well  as  the  ability  to  quickly  place  the  correct 
setting  on  the  gyro  index  and  director,  and  to  correctly  direct 
and  fire  torpeioes  when  ordered. 

207.  Importance  of  weapon.— The  importance  of  the  weapon 
warrants  every  effort  to  make  it  effective  when  an  opportunity 
for  its  use  is  afforded. 

208.  History.— It  is  no  small  part  of  the  duty  of  all  torpedo 
officers  to  systematically  investigate  the  history  of  torpedo 
warfare  before  being  satisfied  with  any  conclusions  as  to  the 
war  method  of  using  the  material  assigned  to  their  charge. 

209.  Maneuvers  and  g'ame  board. — Torpedo  officers  should 
give  their  serious  attention  to  maneuvers  and  game-board 
practice  with  a  view  of  studying  the  part  the  torpedo  can  and 
should  play  in  service.  These  furnish  the  nearest  approach  to 
war  conditions  possible  in  peace. 


CHAPTEK  9. 

HINTS  FOE  TURRET  OFFICERS. 

[Attention  is  invited  to  Chapter  4.] 

210.  Ordnance  pamphlets  and  description  of  mechanism. — 
Ordinance  pamphlets  are  issued  by  the  Bureau  of  Ordnauce 
and  are,  with  drawings  and  descriptions,  liept  on  board  ship 
in  the  custodj'  of  the  gunnery  officer.  Consult  these  for  de- 
tails of  the  mechanism  of  the  battery  at  which  you  are  sta- 
tioned, and  thoroughly  familiarize  yourself  with  all  features, 

211.  Importance  of  duties. — An  officer  given  the  charge  of 
a  turret  must  appreciate  the  importance  of  his  duties  and  of 
the  necessity  for  developing  to  a  maximum  the  efficiency  of 
the  organization  and  material  intrusted  to  his  care.  He  may 
work  hard  and  not  have  the  most  efficient  turret  in  the  Navy, 
but  he  will  never  have  an  efficient  turret  without  hard  work. 
If,  during  peace,  Iiis  guns  fail  to  make  a  creditable  showing 
at  target  practice,  he  is  responsible.  An  energetic  turret 
officer  will  find  ample  work  to  keep  him  busy  at  all  times  with 
the  installation  and  crew  under  his  charge. 

212.  Responsibility. — In  battle,  intelligence,  zeal,  and  cour- 
age are  pitted  against  those  of  the  enemy.  If  the  enemy  is 
of  equal  ability,  but  has  worked  and  thought  to  a  better  pur- 
pose, then  he  will  be  the  victor,  other  conditions  being  equal. 

213.  Methods  to  be  followed. — The  systems  of  training  and 
the  experience  of  past  years  are  all  available  for  information. 
The  development  of  an  expert  turret  crew  is  not  a  mystery. 
It  requires  common  sense,  an  ability  to  judge  and  to  handle 

34776—18 6  81 


82  GUNNERY  INSTRUCTIONS. 

men,  attention  to  details,  study  and  investigation,  and  finally 
hard  work.  The  ability  to  take  advantage  of  opportunities 
that  are  presented  for  training,  -the  formulation  of  proper 
plans  for  training;  and  the  intelligent  carrying  on  of  this 
training  are  the  reasons  for  success  in  gunnery. 

214.  Battery  log. — If  the  turret  log  has  been  kept  up,  read 
it  carefully ;  if  not,  start  one  at  once.  It  will  be  valuable  to 
your  successor  as  well  as  yourself.  It  should  contain  a  record 
of  methods  used  and  the  results  obtained,  summaries  of  target 
practices  and  conclusions  reached,  modifications  to  drills,  and 
whether  or  not  such  modifications  are  improvements,  records 
of  machinery  and  how  repaired,  record  of  tests  of  machinery 
explained  in  detail,  data  relative  to  the  crew,  what  positions 
other  than  their  regular  ones  they  are  capable  of  filling,  and 
any  other  data  which  may  be  of  interest  or  value.  Any 
records  made,  to  be  of  value,  should  be  in  sufficient  detail  to 
be  clearly  understood  by  those  not  familiar  with  the  turret 
or  its  crew.  Do  not  detract  from  the  value  of  the  turret  log 
by  entering  unimportant  remarks,  such  as  "held  loading  drill," 
etc.  Keep  a  record  of  all  measurements  taken,  and  of  all  ac- 
cessories and  spare  parts  provided,  with  their  respective  places 
of  stowage.  Do  not  condemn  a  piece  of  mechanism  until  you 
are  sure  that  you  understand  it,  that  it  has  been  used  as 
designed,  and  has  been  given  a  thorough  trial. 

215.  Inspections. — Frequent  inspections  of  the  entire  in- 
stallation should  be  made  by  the  turret  officer.  These  inspec- 
tions must  be  detailed  and  are  a  constant  check  in  the  routine 
upkeep  of  the  gear. 

216.  Care  in  moving  turret  machinery. — Great  care  must 
be  exercised  in  moving  any  of  the  mechanism  of  the  turret. 
It  is  not  uncommon  for  great  and  sometimes  permanent  dam- 
age to  be  done  because  of  a  lack  of  familiarity  on  the  part  of 
members  of  new  crews.  Caution  in  operation,  when  break- 
ing in  new  men,  Avill  generally  obviate  damage  which  should 


GtrUNERY  INSTRUCTIONS,  88 

have  been  prevented  and  which  will  be  inconvenient  if  not 
Irreparable. 

217.  Material. — The  first  work  to  be  done  upon  assisnraent 
to  a  turret  is  to  clean  and  to  overhaul  the  mount  and  all  parts 
of  the  gear  and  to  check  up  the  stowage  of  spare  parts,  tools, 
etc.  The  division  officer,  junior  officer,  and  turret  captain 
should  familiarize  themselves  with  everything  in  the  turret, 
consulting  blue  prints,  descriptions,  etc.,  freely  and  frequently, 
Everj  detail  of  every  part  must  be  understood.  Never  at- 
tempt to  dismount  or  disassemble  a  part  of  any  mechanism 
without  first  studying  and  learning  the  details  thereof  from 
the  drawings  and  descriptions  that  are  at  hand.  Be  extremely 
careful  in  overhauling  and  in  assembling  mechanisms.  The 
employment  of  force  at  these  times,  which  is  a  natural  tend- 
ency on  the  part  of  one  who  is  not  a  skilled  mechanic,  gen- 
erally does  n)ore  harm  than  good,  and  an  ignorant  man  with 
a  long-handled  wrench,  a  sledge,  or  bar  in  a  few  moments 
may  cause  damage  that  will  take  days  to  repair,  if  it  is  not 
irreparable.  It  is  very  necessary  that  all  gear  be  thoroughly 
overhauled  and  cleaned  before  running,  as  chippings  are  apt 
to  be  present  in  bearings,  which,  if  not  removed,  will  cause 
cutting  and  permanent  injury. 

218.  Use  of  emery. — The  use  of  emery  or  other  gritty  sub- 
stances must  be  closely  watched.  Never  allow  them  on  any 
working  surfaces,  such  as  threads  of  the  plug,  sci-ew  box, 
plug  tray,  gearing,  or  where  they  may  fall  on  bearings.  Be 
particularly  careful  that  such  substances  are  never  used  on 
the  primer  seat,  for  if  this  is  enlarged  fuzed  and  burst  primers 
will  result. 

219.  Lubrication, — Insufficient  lubrication  is  a  general  cause 
of  trouble.  Special  attention  should  be  given  inaccessible 
gearing.  Keep  oil  holes  plugged  with  leather.  Graphite  hoist 
cables  thoroughly.  Keep  oil  always  from  contacts  of  firing 
mechanism  and  primer  seats.  The  kind  of  lubricant  that  is 
used  may  cause  trouble,  as  the  amount  of  lubrication  required 


84  GTHTNERY  INSTErCTIOTIS. 

will  sometimes  depend  on  whether  a  light  or  heavy  oil  is  used. 
Heavy  oil  should  be  used  on  bearings  of  slow  moving,  heavy 
duty  shafts.    Such  bearings  should  be  flushed  out  occasionally 
with  kerosene  to  prevent  the  grease  hardening  in  the  bearing 
and  stopping  the  flow  of  the  lubricant  over  the  entire  bearing 
surface.    All  gears  require  heavy  grease,  such  as  vaseline.    If 
uncased,  they  should  not  be  left  too  long  unattended,  as  par- 
ticles of  dust  or  metal  from  the  gears  frequently  remain  sus- 
pended in  the  grease  instead  of  settling.     Much  used  gears 
will  fi'equently  heat  up  and  soften  the  lubricant  to  such  an 
extent  that  it  will  ooze  out  of  the  gear  box.     In  such  cases 
heavy  grease  mixed  with  powdered  graphite  will  usually  di- 
minish  the   ti'ouble.     Ball   and    roller   bearings   are   usually 
packed  with  vaseline,  but  where  not  sufficiently  inclosed  to 
prevent  the  collection  of  dirt  should  be  carefully  watched. 
Variable  speed  gears  require  a  light  grade  of  pure  mineral 
oil.    Poor  oil  containing  animal  fats  soon  separates  and  leaves 
a  deposit  of  paraffine,  which  is  liable  to  clog  cylinders  or  parts 
and  reduce  considerably  the  efficiency  of  the  gear.    Gun  slide 
bearings  have  frequently  been  found  very  badly  corroded  upon 
dismounting  of  the  gun.     Grease  should  be  forced  in  freely 
before  each  target  practice,  in  order  that  it  may  be  dragged 
into  the  slide  as  much  as  possible  upon  recoil  of  gun.    Trun- 
nions, being  difiicult  to  examine,  are  also  frequently  found  in 
bad  shape.    As  thei'e  is  no  method  of  forcing  grease  into  them 
except  in  some  cases  at  the  top  of  the  bearing,  the  safest 
method  is  to  flush  frequently  with  kerosene,  followed  up  im- 
mediately with  light  oil,  which  will  more  surely  flow  to  all 
parts  of  the  bearing.     Guard  against  leaving  kerosene  in  a 
bearing  or  on  a  metal  surface.    It  sometimes  occurs  that  an  oil 
hole  gets  stopped  up  with  hardening  grease.    The  remedy  is 
obvious.      Turret    captains    frequently    establish    an    oiling 
routine,  and  at  certain  regular  times  go  over  the  entire  turret. 
This  is  a  dangerous  habit,  as  the  amount  of  oil  required 
depends  upon  the  extent  to  which  the  machinery  is  used.    A 


GTJTTNERY  INSTRTICTIOITS.  85 

weekly  oiling  routine,  plus  additional  oiling  for  each  day's 
drill,  is  much  safer.  High-speed  shafts  require  and  should 
receive  more  attention  than  low-speed  shafts.  A  list  of  such 
bearings  should  be  made  and  their  inspection  made  more  fre- 
quently than  the  others. 

220.  Roller  path. — Before  training  tlie  turret  inspect  the 
roller  path  and  see  tliat  it  is  clear  and  well  slushed,  that  the 
holding-down  clips  are  secure,  and  chock  up  all  clearances. 
Roller  paths,  being  difficult  of  access,  are  often  neglected  and 
the  lubricant  used  in  them  frequently  becomes  heavy  with 
dust  and  dirt.  Light  oil  is  more  efficient  than  lieavy  grease, 
as  the  dirt  more  easily  washes  away,  and  there  is  less  drag 
to  the  rollers.  Do  not  let  the  oil  get  so  thin  that  the  upper 
roller  path  becomes  dry.  Roller  paths  and  rollers  should  be 
carefully  cleaned  after  a  visit  to  u  navy  yard  for  repairs  and 
alterations.  Roller  pins  should  be  inspected  and  lubricated 
occasionally  to  see  that  they  do  not  become  frozen  to  the 
roller  path  becomes  dry.  Roller  paths  and  rollers  should  be 
to  the  floating  ring.  The  rollers  tend  to  creep  away  from  the 
center  of  the  turret,  bringing  considerable  ijressure  between 
tlie  inside  flanges  of  the  rollers  and  the  inside  edges  of  the 
roller  paths.  These  bearing  surfaces  will  wear  smooth  and 
become  polished,  and  should  be  inspected  to  see  that  no  burrs 
are  formed  on  them.  In  some  of  the  older  ships  depressions 
have  been  found  in  roller  paths  worn  by  the  rollers,  due  to 
the  fact  that  the  turret  is  always  secured  for  sea  in  one  posi- 
tion, bringing  rollers  on  the  same  spots  on  roller  paths.  To 
avoid  this  danger  the  turret  should  not  be  trained  always  in 
the  same  position  when  not  in  use  except  when  it  is  necessary 
to  secure  it  for  heavy  weather  with  the  locking  pin  or  wedge. 
If  it  is  found  that  the  rollers  creep  around  and  do  not  come 
at  the  same  point  on  the  roller  path  when  the  turret  is  cen- 
tered fore  and  aft,  then  the  above  precaution  is  not  necessary. 

221.  Electric  leads. — The  electric  leads,  terminals,  switches, 
contacts,  circuit  breakers,  etc.,  should  be  carefully  examined. 


86  GUNNEEY  DTSTETTCTIONS. 

See  tliat  the  lighting  circuits  are  in  order  and  that  the  lights 
ill  turrets  and  handling  rooms  are  propqrly  placed.  Have  all 
circuits  tested  weekly  for  grounds.  An  occasional  record  of 
voltage  and  current  used  by  the  various  motors  will  be  of 
value  in  ascertaining  whether  the  machinery  is  working  hard 
or  easy.  If  the  elevating  motor  of  one  of  the  guns  is  using 
three  horsepower  on  a  certain  speed  when  a  similar  motor  in 
another  turret  is  using  only  two  horsepower,  then  a  search 
should  at  once  be  made  to  determine  the  cause  of  such  a  dis- 
crepancy. An  electrical  connection  may  have  loosened, 
blushes  may  not  be  properly  adjusted,  or  the  commutator  may 
be  scarred.  In  case  of  motors  operated  by  controllers  the 
controller  fingers,  if  blistered  or  not  properly  adjusted,  will 
cause  considerable  trouble.  Even  if  fingers  are  smooth  they 
will  need  to  be  gone  over  frequently.  Any  electrician's  hand- 
book will  give  all  necessary  instructions  relative  to  their  care 
and  adjustment. 

222.  Elevating  gear. — The  elevating  gear  should  operate 
very  easily.  If  such  is  not  the  case  it  will  probably  be  found 
that  some  of  the  levers  or  shafting  are  out  of  line  or  bear- 
ings are  badly  adjusted.  Occasionally  the  rack  controlling  the 
"tilting  box"  (Waterbury  gear)  bears  too  heavily  against  the 
pinion.  Sometimes  one  of  the  levers  or  rods  leading  to  the 
pointer's  position  are  sprung  or  bear  against  something.  All 
shafting  and  motors  must  be  adjusted  until  the  mechanism 
will  run  without  any  heating,  and  a  light  touch  on  the  lever 
will  elevate  or  depress  the  gun.  If  the  Waterbury  gear  does 
not  function  exactly  it  should  be  overhauled.  Investigate 
when,  how,  and  by  whom  it  was  installed,  and  its  condition  at 
that  time.     See  that  guns  are  properly  balanced. 

223.  Firing  panel  in  turret  booth, — A  switchboard  should 
•  be  located  in  the  turret  booth  through  which  the  firing  cir- 
cuit should  be  led.     By  means  of  switches  the  turret  officer 
can  accomplish  the  following  on  either  the  battery  or  motor- 
generator  circuits:  (a)  Right  gunfire;   (b)  left  gunfire;   (c) 


GITNNERY  INSTRUCTIONS.  87 

both  gnus  in  salvo,  right  pointer  firing;  (d)  same  as  (c),  but 
left  pointer  firing;  (e)  off  position,  neither  guu  able  to  tire  by 
electricity. 

224.  Signals. — The  system  of  communications  and  of  sig- 
nals siiould  be  thoroughly  investigated  and  understood.  There 
should  be  a  system  of  signals  to  the  pointers  and  trainer  con- 
trolled from  the  turret  officer's  booth ;  also  a  system  of  lights 
and  signals  from  the  booth  to  each  plugman  or  gun  captain, 
and  from  these  men  to  the  turret  officer,  will  be  found  ad- 
vantageous. 

225.  Safety  of  crew. — Make  sure  that  arrangements  are 
such  that  handling-room  crews  may  load  the  hoists  in  perfect 
safety.  Dangerous  traps  cause  unsteadiness  on  the  part  of 
the  crew  and  must  be  eliminated.  The  turret  oflicer  is  re- 
sponsible for  his  crew  and  every  precaution  should  be  taken 
to  avoid  accidents  to  the  members  thereof.  The  plugman 
should  be  carefully  trained  to  watch  for  the  recoil  of  his  gtm 
when  it  is  fired.  AYhen  firing  he  must  not  open  the  plug  of  a 
loaded  gun  until  the  gun  is  discharged,  unless  specially  or- 
dered to  do  so.  In  cases  where  guns  are  fitted  with  salvo  at- 
tiichments  this  may  not  be  necessary. 

226.  Installation  of  dotter. — The  first  installation  of  the 
dotter  is  usually  made  by  the  yard  force.  The  division  officer 
should  understand  the  fundamental  principles  of  the  particu- 
lar dotter.  If  these  are  understood  and  careful  attention  is 
given  to  the  points  vital  to  its  accuracy  at  this  time  a  great 
deal  of  trouble  with  the  device  in  the  future  will  be  avoided. 
The  first  adjustment  often  takes  several  days  and  requires 
patience.  After  it  is  once  made  to  work  and  the  particular 
features  of  the  mechanism  are  understood  but  little  trouble 
should  be  experienced  with  it.  The  dotter  is  a  delicate  mech- 
anism and  at  all  times  requires  care  in  handling.  Bearings 
and  exposed  parts  should  be  kept  oiled  and  properly  covered. 

227.  Running  mechanisms. — All  mechanisms  should  be 
run  daily  by  the  men  who  regularly  operate  them. 


88 


GTTOTTERY  ITISTETJCTIOlSrS. 


228.  List  of  division. — It  will  be  found  very  useful  to  make 
an  alphabetical  list  of  the  tli vision  showing  opposite  each 
name  the  man's  general  characteristics  and  previous  expe- 
rience ;  for  example : 


Brown,  J. 


o.  s. 


Age  20,  strong,  clean,  small,  good  worker,  intel- 
ligent; pre\ions  trade,  farmer;  experience, 
rammer  man  6-inch,  U.  S.  S 


229.  Selection  of  turret  force. — To  each  turret  there  is  as- 
signed a  turret  captain,  electrician,  and  one  or  more  gimners' 
mates.  It  is  desirable  to  supplement  this  force  by  two  or 
more  turret  strikers  who  should  be  carefully  selected  for 
their  intelligence  and  industry. 

230.  Turret  captain. — The  turret  captain  is  the  leading 
petty  officer  of  the  turret  crew  and  should  be  freely  consulted. 
Give  all  orders  and  directions  through  him  and  make  him 
thoroughly  understand  his  responsibility. 

231.  Duties  of  turret  force. — The  turret  force  cleans  and 
cares  for  all  parts  of  the  turret,  mount,  guns,  handling  and 
ammunition  rooms,  and  forms  a  part  of  the  turret  crew. 

232.  Cleaning  bill. — A  cleaning  bill  should  be  drawn  up 
and  posted  showing  each  man's  station  and  for  what  he  is 
responsible,  together  with  the  time  for  overhauling  and  clean- 
ing. The  station  bill  of  the  gun  and  magazine  crews  and  the 
safety  regulations  should  be  hung  in  the  turret  and  handling 
rooms. 

233.  Living  quarters  for  turret  force. — It  is  desirable  to 
have  the  turret  force  live  in  the  turret  and  handling  rooms. 
If  they  can  be  arranged,  metal  lockers  for  the  members  of  the 
force,  and  a  desk  for  the  turret  captain,  placed  on  the  elec- 
trical deck  or  elsewhere  in  the  turret  space,  will  contribute 
greatly  to  the  comfort  and  satisfaction  of  these  men,  who 
should  be  encouraged  in  every  way  to  take  pride  in  the  ap- 
pearance and  condition  of  all  parts  of  the  turret  installation. 


GTmUEEY  INSTETJCTIOUS.  89 

234.  Selection  of  gun  crews. — A  man  shouUl  be  stationed 
In  the  position  that  he  is  best  qualifietl  to  fill.  Each  man 
shouUl  be  trained  for  as  many  stations  as  practicable,  though 
specially  trained  for  his  own  particular  station.  Generally 
the  greater  the  number  of  stations  a  man  is  capable  of  lilling 
the  better  he  is  able  to  perform  the  duties  of  his  own,  and  the 
better  the  duties  of  those  who  may  be  disabled  will  be  absorbed 
by  the  remaining  members  of  the  crew.  The  gun  captain  will 
be  responsible  for  the  service  of  the  gun  in  action.  Gun  cap- 
tains should  not  be  finally  selected  until  the  division  oflicer 
knows  his  men  thoroughly.  A  gun  captain  should  not  be 
recommended  for  examination  until  he  has  been  through  at 
least  one  target  practice  while  acting  in  that  capacity.  IMug- 
men  should  be  strong,  quick,  and  steady.  Men  who  are  men- 
tally quick  should  be  selected  to  run  electrical  gear,  rammers, 
hoists,  etc.  Turret  strikers  are  frequently  desirable  men  to 
assign  those  stations,  as  they  are  generally  familiar  with 
them.    As  a  rule  two  men  should  be  trained  for  each  station. 

235.  Stationing  of  remainder  of  division. — AVhen  the  guns' 
crews  have  been  selected  others  of  the  division  should  be  sta- 
tioned as  powder  passers,  magazine  powder  men,  shellmen, 
etc.  There  are  always  men  in  a  division  who  are  difficult  to 
get  hold  of  at  drill  because  of  their  other  duties.  It  will  be 
found  a  convenience  to  give  them  stations  where  but  little 
drill  is  necessary. 

236.  Pointers.— If  there  are  any  qualified  pointers  in  the 
division  they  should  be  stationed  at  once  in  order  to  permit 
them  to  draw  their  extra  pay.  They  should  be  given  to  under- 
stand, however,  that  they  will  hold  the  position  only  as  long 
as  they  show  ability.  In  trying  out  pointers  remember  that 
appearances  are  deceptive;  do  not  formulate  an  opinion  of  a 
man's  ability  to  point  a  gun  from  his  general  carriage  and 
appearance. 

237.  Preliminary.— The  candidate  should  be  sent  to  the 
sick  bay  (or  to  the  hospital  ship  if  she  is  near  by)  for  eye 
examination.     The  next  step  should  be  iustx-uction  iu  the 


90  GTJirNERY  INSTIlTrCTIOIIS. 

elementary  principles  and  operation  of  the  training  and  elevat- 
ing mechanisms  and  the  most  probable  causes  of  failure  to 
function  properly.  The  location  and  the  operation  of  the 
clutches  for  disconnecting  power  and  connecting  up  for  hand 
operation  should  be  explained.  It  is  a  very  common  mistake 
to  expect  new  men  to  be  familiar  with  mechanical  devices, 
which,  however  simple,  may  appear  quite  obscure  to  them. 

238.  Development  of  pointers. — Having  become  familiar 
with  the  gun  and  its  appurtenances,  the  candidate  should  be 
taught  the  significance  of  the  "  stand-by  "  and  the  firing  sig- 
nals, the  time  interval  to  be  used,  etc.,  the  necessity  of  being 
"  on  "  when  he  fires,  to  "  hold  fire  "  if  he  is  not  "  on,"  and  in 
general  given  a  thorough  knowledge  of  the  system  of  spotting 
and  fire  control.  It  is  not  sufficient  to  tell  a  pointer  tbat  "  the 
bettor  the  pointing  the  poorer  the  results  if  the  sights  are  in- 
correctly set."  He  must  be  told  xcliy.  He  should  understand 
enough  of  the  principles  of  fire  conti'ol.to  know  tcliy  implicit 
obedience  to  the  orders  of  the  spotter  is  necessary,  and  why  an 
attempted  betterment  of  the  spotter's  corrections  will  certainly 
result  in  disaster.  He  should  understand  the  firing  connec- 
tions, the  methods  of  firing,  and  the  safety  precautions.  After 
instruction  has  been  given  the  would-be  pointer  he  should  be 
put  through  exhaustive  tests.  The  time  to  be  spent  on  each 
man  will  vary  considerably,  but  sufficient  time  must  be  allowed 
to  give  each  candidate  a  thorough  and  impartial  examination. 
Too  little  attention  is  sometimes  paid  to  the  consistent  drilling 
of  pointers.  The  turret  should  be  in  a  state  of  preparedness 
at  all  times,  and  should  have  an  adequate  supply  of  expert 
gun  pointers. 

239.  Selection  of  those  to  continue  training. — Some  men 
will  soon  begin  to  do  better  than  others,  the  groups  of  candi- 
dates should  be  rearranged,  putting  the  best  men  together. 
The  best  and  steadiest  should  be  tried  at  training  as  this  is 
the  more  difficult  position.  After  a  few  drills  and  trials  of 
different  arrangements   of  groups   the  poorer  ones   can  be 


GUNNERY  INSTETJCTIONS.  91 

dropped.     During  drills  all  mistakes  should  be  criticized  and 
errors  pointed  out. 

240.  Method  of  scoring. — A  system  of  scoring  should  be 
established.  For  example,  with  everything  stationary  and  the 
sights  "  on,"  pull  the  trigger.  With  the  mark  thus  made  as  a 
center,  describe  two  circles  of  different  radii.  All  hits  in  the 
Inner  circle  can  be  counted  4,  all  those  in  the  next  2,  and  any 
other  0.  The  larger  of  these  circles  sliould  be  small  enough 
to  exclude  any  shots  that  were  fired  when  the  sights  were  not 
xery  nearly  "  on."  This  system  of  scoring  will  arouse  the 
interest  of  the  men  and  will  give  a  basis  of  comparison. 

241.  Officers  to  train  as  pointers. — Turx'et  officers  should 
train  and  ac(iuire  skill  in  gun  pointing.  Only  by  working  the 
gear  themselves  can  officers  learn  the  difficulties  that  tlie 
pointers  experience. 

242.  Beginning'  drills. — When  the  turret  gear  is  in  good 
working  order  drills  may  be  begun.  Remember  the  cautions 
already  given  regarding  the  particular  care  to  be  exercised  in 
running  the  gear  when  breaking  in  a  crew.  Always  inform  the 
turret  captain  sufficiently  in  advance  of  what  the  drills  are  to 
be  to  permit  him  to  prepare  the  gear. 

243.  The  first  drills. — Having  tentatively  stationed  the 
guns'  crews  the  first  drill  periods  should  be  devoted  to  explain- 
ing and  demonstrating  the  gear.  The  men  should  be  taught 
at  this  time  the  general  scheme  of  loading,  the  necessity  for 
precision,  safety  regulations,  nomenclature  of  parts.  After 
these  are  understood  the  individuals  should  be  drilled  in  their 
particular  tasks.  Each  movement  of  each  man  should  be 
studied  until  the  best,  surest,  and  quickest  method  of  accom- 
plishing each  task  is  discovered.  Insist  upon  precision  rather 
than  speed.  The  candidate  for  each  position  should  carefully 
practice  his  part  until  fairly  proficient,  and  then  the  crew 
can  be  given  exercise  in  loading. 


92  GimraERY  HTSTSTJCTIOWS. 

244.  Loading  exercises. — In  the  complicated  power-load- 
ing turrets  save  the  gear  as  much  as  possible.  After  a  load 
criticize  in  detail  each  mistake.  Then  load  once  more  and 
repeat  the  lecture.  It  is  a  frequent  and  bad  practice  to  slam 
through  seven  or  eight  loads,  all  imperfect  in  some  detail. 
With  a  power-loading  turret,  it  is  a  question  of  weeks  or 
months  until  parts  of  the  mechanism  begin  to  become  balky 
because  of  wear  and  tear  on  the  installation.  With  hand- 
loading  turrets  it  is  safe  and  proper  to  load  as  often  as  the 
crews  need  it,  for  no  harm  can  come  to  the  gear  except  to  the 
breech  mechanism. 

245.  Timing-  loads. — As  soon  as  the  crews  can  load  with 
precision,  begin  to  pit  them  against  one  another.  Speed  in 
loading  is  the  natural  result  of  precision  and  team  work.  In 
the  event  of  mishaps  always  have  the  fault  remedied  as 
would  be  the  case  in  service,  and  always  complete  every  load 
that  is  attempted.  The  time  should  be  taken  from  shot  to 
shot  as  seconds  saved  in  loading  may  be  readily  lost  by  the 
pointer. 

246.  Priming. — The  plugman  should  practice  priming  many 
times  a  day  until  proficient. 

247.  Powder  passing. — If  the  powder  is  passed  by  hand, 
the  passers  should  be  required  to  pass  at  least  50  bags  a  day. 
This  can  be  accomplished  by  sending  the  bags  up  on  one  side 
of  the  turret  and  down  on  the  other.  Care  must  be  exercised 
to  always  have  the  strap  end  of  the  bag  uppermost,  and  that 
this  strap  is  not  used  in  passing  the  bags.  The  powder  passers 
should  be  drilled  daily  until  they  are  developed,  and  can  con- 
tinue their  duties  without  becoming  fatigued.  Every  indi- 
vidual wlio  handles  the  powder  must  understand  that  the  igni- 
tion end  of  all  bags  when  loaded  must  be  toward  the  breech. 
Instruction  must  be  given  regarding  the  care  to  be  taken  in 
handling  bags— the  breaking  of  a  single  powder  bag  may  inter- 
rupt or  delay  the  firing  and  should  not  occur. 


GTnOTERY  INSTRTTCTIOTrS.  93 

248.  Requirements  at  drill. — Some  of  these  are  thorough 
seating  of  the  shell,  the  loading  of  powder  bags  with  ignition 
ends  toward  the  breech,  complete  closure  of  breech,  insuring 
closing  of  contract  in  firing  circuits,  no  skylarking  or  un- 
necessary noise,  the  completion  of  every  load  commenced,  the 
simulation  of  actual  firing  conditions,  use  of  regular  signals 
and  methods  of  communication,  the  closing  of  the  turret 
hatches  and  doors  as  would  be  the  case  in  service.  Give 
"  silence "  frequently ;  develop  spirit  of  responsibility  on 
part  of  gun  captains  and  members  of  the  crew.  Exercise  at 
casualties. 

249.  Casualties. — The  best  way  to  avoid  casualties  is  to 
make  a  list  of  such  as  you  can  learn  of  having  occurred  in 
other  turrets,  and  of  any  others  that  can  be  conceived.  Note 
the  remedy  and  drill  accordingly.  The  following  are  some  of 
tlie  casualties  that  may  occur  with  remedies : 

(a)  Misfires. — Train  the  firing  pointer  to  be  sure  he  tries 
both  motor-generator  and  battery-firing  circuits  before  he 
calls  "  IMisfire."  If  both  circuits  fail,  fire  by  percussion.  If 
the  primer  does  not  fire,  shift  primers  and  try  again  by  elec- 
tricity. One  member  of  the  crew  should  be  drilled  to  watch 
the  lock  and  observe  whether  the  primers  fire. 

Recent  records  show  that  where  misfires  have  occurred  they 
have  generally  taken  place  for  the  reasons  stated  below: 


94 


GTnOTERy  USrSTRTTCTIOIIS. 


Failure  of  pointer 
to  malcp  pnntn.pt 

Failure  of  circuit 

Failure  of  charge 

Failure  of  prim- 

(70 per  cent). 

(20  per  cent). 

(8  per  cent). 

er  (2  per  cent). 

1.  Saueezed  grip  in- 

1. Circuit  bro\'en. 

1.  Last  section 

1.  Primer  not 

stead  of  trigger. 

(o)  Beforefiring,not 

shoved  too  far 

seated. 

2.  Pushed  button 

carefully  gone 

from  m ush- 

2.  Imperfect 

sideways  in- 

over and  tested. 

room. 

manufac- 

stead of  straight 

(6)  During  firing, 

2.  Last  section  in- 

ture. 

down. 

jarred  out  of 

serted  ignition 

3.  Using  percus- 

3. Made  contact  be- 

place,    jammed 
between     mov- 

end forward. 

sion    for 

fore   order 

3.  Charge  wet. 

electric,    by 

"Ready"      was 

ing  surfaces. 

mistake. 

given;  i.  e.,  be- 

(c) Allowance  for 

fore  breech  was 

recoil    insufli- 

fully  closed. 

cient. 

{d)  Too  much  tape 
on    terminals- 
hides  an  evident 
flaw. 

(c)  Terminal  on 
plug  held  back 
,  when     plug     is 
closed  by  short 
leg  wc'dgiug 
down  on  face  of 
breech  next  to 
binding  post. 

2.  Insufficient    cur- 

rent. 

(a)  Battery  charged 
iand  allowed  to 
run  down. 

(b)  Motor  generator 
grounded. 

3.  Dirt,  grit,  or  oil  on 

contact  pieces. 

(&)  All  lights  in  turret  and  handling  room  out. — Use 
small  batlery  hand  lamps  that  are  provided.  The  crews 
should  be  drilled  to  be  able  to  load  in  absolute  darkness, 
slowly  but  completely.  This  particular  casualty  has  happened 
a  number  of  times  and  has  usually  been  unprovided  for. 

(c)  Gas  ejecting-  system  carries  away  or  air  valve  fails. — 
'Use  auxiliary  air  line.  Be  very  careful  about  giving  "bore 
clear." 

(d)  Fire  in  any  part  of  turret  or  handling  room. — Get  all 
powder  away  from  scene  of  fire  and  into  barrels  of  water  or 


GUITNERY  nsrSTKirCTIONS.  95 

shell  rooms  behind  closed  dooi'S.  Keep  all  magnzine  doors 
closed.     IMan  the  fire  hose. 

(c)  Broken  powder  bag. — Stop  all  gear  on  that  side.  If 
badly  broken,  gatlu-r  up  powder  and  throw  it  into  bucket  of 
water ;  if  only  a  small  break,  gather  up  powder  and  throw 
into  gun. 

(/)   Broken  rammer. — Use  hand  rammer. 

(fif)  Plug  won't  close. — Open  plug  to  see  if  powder  bags  ure 
shoved  in  far  enough  and  ti*y  again.  If  this  is  not  the  trouble 
try  to  locate  the  cause  and  remedy  it.  Look  for  burrs,  bent 
hinge  pin  or  plug  tray,  or  jammed  operating  shaft. 

(/()  Plug  sticks. — Nut  on  mushroom  stem  may  be  set  up 
too  hard,  causing  split  rings  to  expand  and  bind  on  gas  check 
seat.  It  is  possible  that  the  inner  bearing  of  the  shaft  carry- 
ing the  worm  is  bound  by  particles  of  metal  worked  into  the 
lower  part  of  the  bearing,  making  it  impossible  to  open  the 
plug  without  disassembling  the  operating  mechanism,  which 
should  be  done  at  once. 

(/)  Powder  bags  come  up  wrong  end  first. — Reverse  and 
load  as  usual. 

(;■)  Shell  hoist  cable  carries  away. — Provide  shell  from 
other  side  until  new  cable  is  rove  olT. 

{k)  Circuit  breaker  blows. — Put  controller  on  "off"  posi- 
tion and  throw  in  circuit  breaker. 

(?)  Signal  bells  and  buzzers  gone. — Use  voice  tubes  from 
turret  oHicer's  booth  in  connection  with  telephone. 

(m)  Burning  fragments  of  powder  bag  on  mushroom 
head. — Sponge  off  carefully  with  wet  sponge.  Be  careful  that 
"bore  clear"  is  not  given  before  it  is  removed. 

The  above  are  but  a  few  of  the  many  contingencies  that 
must  be  prepared  for. 

250.  Difficulty  in  seating  shell. — If  the  gun  is  elevated  or 
has  a  steep  compression  slope  there  n:ay  be  trouble  in  mak- 
ing a  shell  stick  when  seating  it.     With  such  the  case,  a 


98  GTHOTERY  rNSTRUCTIONS. 

grommet  of  small  twine  around  the  shell,  just  forward  of  the 
baud,  will  insure  it  sticking. 

251.  Powder  charge  left  in  gun. — If  it  is  apparent  that  the 
gun  is  not  to  be  fired  promptly  the  charge  should  be  removed 
and  kept  at  the  temperature  of  the  magazines.  Otherwise  the 
charge  will  take  up  the  temperature  of  the  chamber,  resulting 
in  an  I.  V.  above  or  below  the  normal. 

252.  Excessive  oil  in  screw  box. — Do  not  fire  a  giin  with 
the  screw  box  and  breech  plug  threads  covered  with  grease 
or  oil.  When  fired  in  this  condition  the  set  back  will  tend 
to  unlock  the  plug  and  carry  away  worm,  the  pinion,  aud  other 
parts  of  the  mechanism. 

253.  Unburned  frag'ments  in  chamber. — Unburned  tape  is 
frequently  found  in  the  chamber  and  bore  of  guns  that  use 
hags  bound  with  woolen  tape.  This  tape  sometimes  smoulders 
after  the  breech  is  open,  and  constitutes  a  grave  source  of 
danger. 

254.  Clearing  vent.— It  is  seldom  necessary  to  clear  the 
vent.  If  it  becomes  necessary,  use  the  priming  wire  from  the 
forward  end.  Carefully  avoid  scoring,  and  thoroughly  clean 
the  primer  seat. 

255.  Eay  filters. — Attention  is  invited  to  the  ray  filters  for 
use  in  sight  telescopes.  These  should  be  kept  at  hand  near 
the  guns  and  used  when  pointing  into  the  glare  of  sunlight 
or  at  a  searchlight. 

256.  Removal  of  tompion. — Be  sure  to  remove  tompion 
before  a  primer  is  fired,  otherwise,  it  may  be  lost  overboard. 
If  left  in  gun  when  the  latter  is  fired  the  muzzle  may  be  blown 
off. 

257.  Refilling  shell  racks. — During  an  engagement  take 
advantage  of  every  cessation  of  fire  to  fill  turret  shell  racks. 

258.  Talks. — Drills  should  be  interspersed  with  talks  on 
target  practice,  aud  the  end  in  view,  which  is  preparedness 
for  battle.  The  men  should  be  questioned  regarding  safety 
precautious  and  casualties.    They  should  be  given  general  in- 


GUNNERY  INSTRUCTIONS.  97 

forniatioi)  regarding  the  ordnance  gear,  the  action  of  the  gun 
wlion  tired,  the  method  of  talking  up  the  recoil,  weight  of  shell 
.Hid  (liiHTf'-  Tlit>  tlieory  of  tiro  control  nntl  spotting  should 
he  explained,  and  the  effects  of  inaccuracy  of  pointing  demon- 
strated. 

JUNIOR  DIVISION  OFFICERS. 

259.  Suggestions  for. — CJiven  a  well-organized  turret  di- 
vision, a  lieutenant  in  command,  you  are  ordered  to  this  di- 
vision as  jmuor  oflicer.  Upon  joining  ship,  division  officer 
ord(>rs  yon  to  Candiarize  yourself  with  the  turret  and  crew  as 
soon  as  possil>l<\  The  turret  officer  may  make,  with  you,  a 
llioroimli  insjiection  of  the  turret,  pointing  out  the  general 
s.lienie  of  loading,  the  stowage  of  anununition,  the  parts  or 
pl.Mces  he  has  foniul  needing  particular  care,  and  the  assign- 
ment of  vari((us  ]>arts  to  the  gunner's  mates  and  their  help- 
ers, i.jiy  o\it  a  plan  of  study  for  yourself  and  stick  to  it  so 
tar  as  your  other  duties  permit. 

The  following  is  an  example  of  such  a  plan.  Any  one  which 
completely  covers  the  entire  installation  will  he  satisfactory. 

First  day. — Go  o\er  the  general  arrangement  of  the  turret, 
I  1  )  note  method  of  sujtply  of  ammunition  and  (2)  access  to 
linndling  room.  Ci)  draw  a  plan  of  magazines  and  shell  rooms 
with  positions  of  flooding  and  sprinkling  valves  on  decks 
ahove.  (4)  examine  barbette  inside,  noting  which  parts  re- 
volve with  turret  and  which  are  stationary,  (5)  note  methods 
of  securing  turret  for  sea  in  order  to  tell  at  a  glance  whether 
turret  is  ready  for  training  or  not.      (Wedges,  center  pins, 

etc.) 

Second   day. — Examine   turret   turning   mechanism ;    where 
l)lace(l,  how  many  sets  of  motors,  where  controlled,  how  shift 
from  power  to  hand,  how  set  up  on  friction  gear  (read  pamph- 
lets descrihing  the  gear). 
34776—18—7 


98  GUNNERY  INSTRUCTIONS. 

Gun-elevafiug  mechanism,  where  placed,  where  controlLed 
and  method  of  transmission  of  control,  how  shift  from  power 
to  hand  elevating,  wliat  the  friction  fiear  is,  and  how  set  up, 
how  balance  a  sun.  i.-  c..  whetiier  when  loaded  with  shell  and 
drill  charge,  the  gun  is  balanced  and  if  not,  why  not  (sub- 
caliber  attachments  may  be  in  place).  Examine  trunnions 
and  wed,t;"es.  note  whether  ;j:uns  are  on  knife  edjj;es. 

Third  day. — Sijilits  and  mechanism,  routine  <»f  oiling:  and 
cleaning  the  working  parts.  Mark  of  telescope,  method  of 
protection  from  dampness,  how  focus  for  dotter  work,  how 
shift  sights  when  bore  sighting. 

Fourth  day. — Recoil  mechanism;  liow  many  cylinders,  how 
many  springs  in  each,  principle  of  action,  position  of  cylin- 
ders, how  liquid  is  supplied.  Amount  of  recoil,  and  how  firing 
circuit  and  gas  ejecting  hose  are  fitted  to  allow  for  recoil. 

Fifth  day. — Firing  circuit.  How  many  methods  of  tiring. 
how  connected,  what  breaks  in  circuit  and  where,  whether 
each  pointer  can  fire  his  own  or  both  guns  and  how  this  is 
accomplislied.  Where  motor  generator  is  placed,  where  stor- 
age battery  is  secured,  kind  of  battery  and  characteristics. 
How  fire  by  percussion,  what  kind  of  primers  are  used,  trace 
each  lead  of  circuit,  and  note  its  use. 

Sixth  day. — Brpecli  nieclianism.  Dismount  and  examine 
parts  of  mechanism,  function  of  each,  method  of  operation, 
safety  devices,  mushroom  pad  and  rings,  their  object  and 
method  of  adjustment.  Note  particularly  the  wedge  of  the 
lock  and  extractor  and  test  a  primer  in  tlie  lock  to  see  if  it 
is  possible  to  insert  primer  beyond  extractor,  and  how  avoid 
this. 

Seventh  day. — Miscellaneous  subjects  : 

(a)  Roller  paths,  condition  of  rollers;  they  nnist  be  free  to 
revolve  on  pins.  See  nuts  on  holding  down  clips  free  of  rust, 
path  well  greased. 

(5)  Ventilating  system.  Where  supply  is  obtained,  and 
path  of  air  circuits  in  handling  room  and  turret. 


GUNNERY  INSTRUCTIONS.  99 

{!•)    WIhmt  (lr;iiiis  lend  (roii:  l);n'l)('tt('  and  linndling  room. 

( '/ )  .\(l.jus(  iiiriit  .111(1  (ipcnit  ion  of  dotfcr  .^r;ir.  Thi.s  can  ho 
.stiKlicd  host  iit  th'ill. 

(r)  Soui'co  of  .supijly  of  coiniircsscd  ;iir  for  ^iiis-o.jocting 
.sy.stoin,  Mild  loc.-itioii  of  accuiiiulalor  and  lead  from  il  lo  f:tii\s. 

(/)  As  opportunity  offers,  read  ovor  the  battery  log.  uotinfr 
Ihi'  miinher  and  kind  of  drills  you  can  expect  to  have,  the 
records  of  last  hrinj:.  scores  made,  any  interruptions  or  acci- 
dents that  oujiht  to  he  avoi<le(l  in  future,  any  remark.s  on  the 
practice  made  hy  the  battery  officer. 

((/)  IMak(>  an  ins])ection  of  the  suhceiitral  ( ,:,'et  the  elec- 
trician in  ciiai-j;e  of  the  plant  to  accomi)aiiy  you).  Find  out 
how  battle  orders  are  commnnic-ited  lo  the  turret.  General 
arrangement  of  central,  snhceiilral.  and  subs. 


chaptp:r  10. 
hints  for  officers  of  a  broadside  battery. 

260.  General. — Many  of  the  remarks  in  the  cliapter  "Hints 
for  tui-rei  ofhrers  "  are  pertinent  for  an  officer  assigned  to  a 
broadside  battery.  Tliis  l)attery  constitutes  an  important  part 
of  the  armament  of  the  ship. 

261.  Organization  and  drill. — Tlie  organization  and  suc- 
cessful H(hninist ration  and  drill  of  a  broadside  battery,  com- 
posed of  guns  frequently  widely  scattered,  require  the  closest 
attention,  and  many  ot1ic<'rs  consider  that  it  is  a  more  difficult 
task  tlian  the  development  of  a  turret  unit,  where  the  crew 
and  materia]  are  all  closely  as.sembled. 

262.  Material. — The  details  of  the  material  assigtH>d  the 
division  nuist  be  thorouglily  learned  and  every  accessible  part 
examined  and  put  in  order. 

263.  Lining  up. — It  is  presupposed  lliat  llie  guns  have  been 
pi-o])erly  lined  up  and  balanced  when  installed.  The  lining 
up  may  l)e  checked  when  the  shiji  is  in  dry  dock.  Too  much 
clearance  l)etween  trunnions  and  trunnion  seats  or  cap  squares 
may  be  taken  up  by  screwing  in  on  tlie  wedges  fitted  for  the 
purpose.  Excess  of  clearance  may  be  detected  when  the  gun 
is  being  trained  in  either  direction  by  suddenly  reversing  the 
direction  of  train. 

264.  Running  in. — The  guns  should  lie  run  in  and  the 
roller  paths  carefully  examined  for  liaws.  cracked  rollers, 
etc.  The  recoil  cylinders  should  be  opened  and  cleaned  and 
springs  closely  examined. 

100 


GUNNERY  INSTRUCTIONS.  10. 

265.  Firing-  circuits. — -In  iiri'i'iii'in;;'  ;;uii  for  lirin^,'.  tlie  elec- 
tric tiring'  circuits  should  be  Ihoroutfhly  overhauled.  Wipe 
off  all  connectlous  with  alcohol  or  gasoline  to  free  them  from 
dirt  and  j^rease,  comiect  up  leads,  and  rinj,'  through  with  a 
magneto.  If  circuit  is  found  continuous,  then  connect  a  volt- 
meter in  series,  close  lirst  ou(^  tiring  key  then  the  other  and 
note  voltage  given  l)y  both  motor  generator  and  battery; 
should  be  about  20  and  1(»  respectively.  As  a  tinal  te.st  fire 
a  drill  primer  with  each  circuit,  first  seeing  primer  .seat 
wiped  clear  of  greasq  and  oil.  Tape  all  connections  around 
breech  to  prevent  possibility  of  grounds. 

266.  Friction  disks. — Di.smount  elevating-friction  disks, 
wash  with  lye  water,  ;ind  clean  with  silicon  to  remove  all 
grea.se.  Iieasseml)le  and  set  up  as  taut  as  can  be  done  by  one 
m;in  with  a  i;4-inch  wrench.  If  this  is  not  done  the  tendency 
of  the  muzzle  to  .iumji  on  lii-ing  will  throw  the  breech  down. 
During  tiring  leave,  the  cover  off  the  gear  case  and  split  pin 
out  of  the  nut  so  that  if  friction  disks  slip  they  may  be  set 
up  again  without  lo.ss  of  time. 

'i'he  training  disks  should  be  .set  ui)  to  grip  the  arc  tight 
enough  to  prevent  siii)i)ing  when  the  direction  of  train  is  re- 
\ersed  suddenly.  The  niain  precaution,  liowever,  should  be 
to  keep  the  arc  at  all  times  free,  of  oil  or  water. 

267.  Breech  mechanisms. — Dismount  and  examine  breech 
mechanism  carefully.  Examine  gas  check  pad  for  cracks, 
smear  well  with  tallow,  and  set  up  hand  taut.  Have  a  can  of 
tallow  at  hand  for  this  purpose  during  firing.  See  split  rings 
turned  with  splits  at  opposite  ends  of  diameter.  See  primer 
vent  clear  in  wedge  of  firing  lock.  See  that  firing  pins  are 
sti-aight.  imbroken,  and  clear  of  seat  In  wedge. 

268.  Gas-ejector  system. -Turn  air  on  gas  ejector  and  ex- 
amine line  for  leaks.  In.spect  nozzles.  Do  not  forget  to  re- 
move tompion  before  doing  so. 

269.  Fire  control.— The  fire-control  leads  and  devices  must 
be  uuderstood  by  the  entire  division. 


102  GUNNERY  INSTRUCTIONS. 

270.  Ammunition  supply. — Tlie  •  aamuinition  supply  for 
Uiins  is  au  iiiiiiorliiiit  matter  that  should  receive  careful  con- 
*ii(lerati()ii.  There  is  a  .^real  deal  of  detail  connected  with  the 
sup]»l,v  of  aiiiumiiiiioii.  the  (tpeninn'  of  cases,  the  disposal  of 
boxes,  wiping  olf  of  cartridj^es,  etc..  wiiicii  will  require  prepa- 
ration and  j;ood  organization. 

271.  Selection  of  crew. — l<'or  7-inch  guns  the  rammer  men 
should  he  tall  men.  long  armed,  and  of  :iverage  strength.  First 
and  second  tray  men  should  he  good  strong  men.  the  strongest 
of  the  division,  as  the  speed  of  the  loading  depends  on  them. 
Small   men  are  best  for  ]irimer  men. 

272.  Routine  of  drills. — To  drill  a  large  broadside  battery 
the  work  must  be  mai)p;\l  out  ahead.  One  olMcer  can  not  run 
the  whole  drill,  each  gun  captain  nuist  do  his  i»art.  The  (httter 
and  the  drill  gun  should  be  made  ready  before  quarters. 
When  drill  call  sounds  send  the  gun  crews  to  the  loading 
machine  and  the  pointers  to  the  dotter.  One  otticer  takes  the 
loading  crews   while  another  takes  the  pointers. 

273.  Detail  of  pointer  drills — Mechanical  target. — In  the 
early  stages  all  drill  will  be  with  the  mechanical  targets. 
l>etermine  on  the  dotter  cards  the  area  which  indii-ates  a  hit 
and  mark  all  cards  accordingly.  It  is  not  well  to  have  the 
pointer  tire  too  many  shots  at  a  time.  .\  string  of  the  ninn- 
ber  of  shots  he  will  lire  at  practice  is  best.  High-power 
glasses  are  trying  to  the  eyes.  lOorty  shots  for  a  pointer's 
morning  work  is  enough,  which  means  double  that  number 
when  the  time  at  the  trainer's  sight  is  considered.  ,  If  a  bull's- 
eye  is  available  make  the  pointers  get  well  in  the  black.  The 
target  is  oidy  of  such  size  that  it  will  catch  all  shots  aimed 
at  the  bull's-eye.  In  case  of  donltt  coimt  a  miss.  Use  a  buzzer 
attaclied  to  the  tiring  key  and  also  have  the  pointer  sing  out 
"tire"  to  stimulate  percussion  tiring.  Figure  out  all  scores 
with  meclianical  targets  or  check  sights  and  post  the  results 
on  the  bulletin  board  daily.  Keep  record  in  a  book  and 
average  by  week  and  month.     Do  not  make  the  firing  signal 


GUNNERY  INSTRUCTIONS. 


103 


loo  short  !i)  first.  iM'ill  llic  li;ittt'i-y  in  hrojidsidc  liriiiu  l)y 
sciidiui;  ii  iii;iii  to  tli(>  sul)si;iti<>ii.  Let  liiiii  wear  :i  plioiio  and 
l)e  in  conunnnication  with  a  man  on  the  aun  (U'ck  who  will 
;;ive  the  stand-l).v  and   tiriny  sijjnal. 

274.  Cards  for  recording  performances  of  gun  pointers. — 
The  following;  tyiu's  of  cards  have  Ix-eii  ustMJ  with  success,  and 
are  i-econuiiended  l)y  a  jrunnery  officer  for  la'cpiui,^  a  record 
of  the  woi-k  of  pointers  with  tlie  dotter  : 

(Obverse.) 


Name 

SCORES  MADE  ON  BECOBD  STBINGS. 

Date. 

Score. 

Date. 

Score. 

Date. 

Score, 

[This  side  may  be  lillett  in  with  pencil. 


104  GUNNERY  INSTRUCTIONS 

(Reverse.) 

GUNNERY  RECORD  CARD. 

Name, 

Rate,   ,  Division,   

Gun, 

Station, 

Date  of  detail,   

Qualified  as 

Date  of  expiration, 

Small  arms  qualification, 

Notes 


(Fill in  this  side  with  ink.     St^  instniutious  fur  Iceepiugthese  cards. 
Turn  in  to  gunnery  officer  at  end  of  weelc,  and  wlien  completed. 1 


GUNNERY  INSTRUCTIONS,  106 


Name.. 
Rate... 

TURRET 

DOTTER  TARGET. 

i 
1 

1 

Date -     

Full 

size 

Score. . 

C 

] 

yards. 

of  target 

,  30  t.y 

GO  f. 

-et  at  7,000 

3  AND  6  INCH  DOTTER  TARGET. 

Name 

Hate 

Date 


n 


Score . 


White  bull's-eye  counts  5;  black  border  3; 
outside  0. 


Full  size  of  target  15  by  15  feet  at  2,000  yards.  Elementary 
Practice,  191:5.  C)l)taiti  targets  from  armory.  Enter  score  ou 
Guimery  Record  card  and  give  target  to  pointer.  Record  strings 
must  be  fired  under  the  e.vact  standard  conditions  prescribed  by 
the  Gunnery  Othcer. 


106  GUNNERY  INSTRUCTIONS. 


3  AND  6  INCH  DOTTER  TARGET. 


n 


Full  size  of  target,  21  by  15  by  25  at  4,000  yards. 


275.  Misfires,  hangfires,  safety  precautions. — Triiin  the 
tiring-  pointer  to  he  sure  he  ])re8ses  both  the  motor  generator 
and  the  battery  tiring  key  before  he  calls  "  misfire."  Train 
tlio  gun  captain  to  tii'e  by  percus.sion  at  the  oi'der  of  the 
pointer.  Train  him  to  shift  primers  when  all  three  methods 
have  failed  to  fire  the  gun.  Train  the  rest  of  crew  to  stand 
clear  while  i)rimer  is  being  shifted. 

Train  the  crew  never  to  open  the  breech  of  a  loaded  gun 
aftei'  an  attemi)t  lias  been  made  to  fire  it,  without  orders  from 
tlie  l)attery  officer.     ( See' Naval  Instructions  1913,  art.  2858.) 

276.  Loading  drill. — The  drill  gnu  nnist  be  used  daily. 
I'rom  1<»  to  '20  loads  ai"e  enough.  Reward  the  best  crews  by 
shortening  the  number  of  loads.  Time  each  load  from  the 
order  "load"  until  the  i)lug  is  primed  and  closed.  Average 
tiie  times  and  post  on  the  bidletin  l)oard.  After  the  loading 
drill,  work  the  primer  men  witli  their  ])lugmen  at  the  drill 
gun.  l^et  each  jtrimer  man  place  2."  to  50  primers  daily.  Im- 
press the  crew  th;it  there  is  no  danger  and  that  they  are  as 
safe  just  beyond  the  linuts  of  the  gun's  recoil  as  anywhere  in 
the  comi)artment.  I'articular  attention  must  be  given  to  the 
plugman.  He  nnist  invariably  comiiletely  close  the  plug  to 
avoid  a  misfire,  and  must  stand  and  move  in  a  way  that  will 
obviate  interfei'ence  with  the  loaders  and  at  the  same  time 
clear  the  recoil  of  the  gun. 

277.  Sight  setting. — Send  out  ranges  through  the  visuals 
and  telephones.     Have  each  sight  setter  at  his  own  gun,  and 


GUNNERY  INSTRUCTIONS.  107 

li.-ivc  the  uun  i"ipl:iin  rt'cmd  cnrli  liinjic  mid  dofU'ction  us  sot. 
I-'r<iin  1.")  lo  liO  r.Mimcs  ••ii-c  i'iiuiiltIi.  'I'liis  is  in  jidditidn  to 
iiidividiiiil  instruction  nnd  drill.  It  is  iniiiortaiit  that  the 
(illiccr  of  tlif  divisidn  slmiild  (•licci<  the  ranjivs  as  received  from 
the  substation.  In  training  for  lonji-ranjie  firiufi  it  is  a  good 
idea  to  liave  tlic  sights  sot  at  the  i>rol)ah]<>  tiring  range  to 
accustom  tlio  jMiintors  to  \vorl<ing  with  the  gun  constantly  in 
elcvat  ion. 

278.  Afternoon  work. — Tlic  afterno(m  period  is  best  de- 
voted to  ligiit  worlc.  For  instance,  liave  pointers  tire  a  strln.g 
or  two  ajiiece  and  drill  the  loading  crews  again  that  were  a 
liit  off  in  llie  morning.  Stoii  drill  in  time  to  lot  the  men  rest. 
There  is  ideiity  of  time  dui'ing  di-ill  pei'iods  lo  get  in  the  work 
if  it  is  done  i)roi)erl.v.  Demand  as  military  and  dean  ap- 
pearance during  target  practice  as  at  any  other  time.  If  there 
is  going  to  he  a  loading  drill  after  quarters,  adow  the  men  , 
five  minutes  to  shift.  Shells  are  usually  .greasy,  and  it  does 
no  good  to  have  the  men  ruin  their  uniforms. 

279.  Night  drills. — As  this  battery  is  an  important  part  of 
the  torpedo-defense  armamenl.  the  pointers  and  crew  must  he 
exercise<l  after  dai-k.  .\  station  hill  for  lookouts,  gun  crews, 
and  tire  control  when  in  the  jiresence  of  an  enemy  nnist  be 
I)i-epared. 

280.  Difficulties  in  assembling'  men. — .\  battery  officer  will 
find  it  hard  to  get  every  man  of  the  division  at  the  same  time. 
Make  petty  ofhcei's  and  the  .uun  captains  resi)onsible  for  get- 
ting the  crews  ui)  pi-omjitly.  Arrange  the  details  for  the  day 
calls,  working  iiarties,  etc.,  by  gun  ci'ews.  If  details  miss  drill 
in  the  forenoon  they  can  be  drilled  in  the  afternoon.  Watch 
the  division  list  closely.  The  gun  captain  or  the  pointers 
should  iKtt  be  detailed  as  coxswains  of  boats.  Assign  men  of 
unimportant  stations  as  boat  keepei-s,  etc. 

281.  During'  practice. — The  crews  should  he  at  their  sta- 
tions well  ahead  of  the  time  and  all  precautions  and  regula- 
tions i-equired  for  general  quarters  carrieil  out.     See  that  the 


108  GUNNERY  INSTRUCTIONS 

lirimei-  men  huve  a  supply  of  tested  primers.  Fire  a  primer  iu 
viu-h  gun.  The  primer  men  sliould  liave  Ijeen  instructed  never 
to  piclv  up  a  primer.  Remind  tlie  pointers  of  tiie  target  at 
wliicli  tliey  are  to  tire.  Note  the  reading  of  the  sights  at  the 
liulsli.  ('lieck  the  timekeeper.  Explain  to  the  umpire  before 
you  start  in   what  order  you  wish  to  tire  the  guns. 

282.  Procedure  before  and  during  battle  practice. — This 
will  folldw  the  same  general  scheme  as  elementary  practice, 
and  most  of  the  prei^aration  for  battle  practice  will  have 
already  been  covered.  All  fii-ing  is  by  signal.  Subcaliber  by 
single  guns  and  in  salvo  is  used  in  preparation,  together  with 
check  sights.  All  orders  .should  l)e  given  through  the  fire- 
contnil  phones.  This  can  be  arranged  by  having  <me  of  tlie 
ilivision  ollicers  run  the  substation.  Loading  is  equally  as 
important  ;is  in  other  forms  of  practice,  and  the  crews  .shi>iild 
.become  accustomed   to  loading  with  guns  in  elevation. 


CHAPTEK   11. 
TORPEDO  VESSELS  AND  SUBMARINES. 

283.  Essentials  of  training. — Tho  general  sy.steni  ol'  ti;iiii 
iii.i:  oul lined    in  prevuuis  cliapters  (>l)taiiis   Un-   tliese  ves.sels. 
Kssciitial    iiKKlilications   iiiiisl,   however,   l»e    introduced    in   de- 
tails. 

284.  Artificiality  of  peace  exercises. — Tlu>  i)eace  exereiyes 
given  lo  vessels  of  these  classes  partake,  to  a  very  considerable 
degree,  of  artiticiality  IxM-anse  of  the  absence,  to  some  degree, 
in  tlieni  of  the  high  tension  and  nervous  strain,  which  will 
lie  Ihe  most  ixitent  factor  in  the  oitei-ation  of  these  craft  and 
of  their  armaments  in  war.  The  ranges  in  practice  for  both 
gun  and  torpedoes  are  long,  imjiosing  some  difficult i(\s.  It  is 
not  intended  that  this  training  sliouhl  teach  that  such  are 
necessarily  to  be  the  I'anges  for  liattle. 

285.  Lessons  of  Russian-Japanese  War. — A  lesson  of  the 
recent  struggle  in  the  Far  East  is  that  generally  an  attack 
with  torpedoes  by  the.se  classes  of  vessels  at  night  must  be 
driven  home,  and  th(>  torpedo  range  must  be  one  where  hits 
(ire  (iHHured.  The  development  of  the  long-range  torpedo  will 
l)robal)ly  give  thes(>  vessels  a  ]iew  and  wider  role  in  future- 
day  action. 

286.  Gun  on  destroyer. — While  the  torpedo  is  the  ma.ioi* 
weapon  of  the  tori)edo  vessel  the  gun  on  the  destroyer  must 
not  be  neglected.  We  have  numerous  instances  in  war  of  the 
use  of  the  destroyer  for  other  purposes  than  that  of  defeating 
torpedo  boats  and  of  delivering  torpedo  attacks.  Many  oc- 
casions may  be  exi)ected  to  arise  \^hen  quick  and  accurate 
shooting  will  become  necessary. 

109 


110  GUNNERY  INSTRUCTIONS. 

287.  Destroyer  actions.  -'J'lir  I'dllowiii.u  .-irr  cx^iiniilrs  of  re- 
tviit   (h'slroyor  ncl  inns  : 

On  tlu'  ni.nlit  ol"  iMjutIi  !).  1!)04,  four  Russian  and  four 
Japanese  destroyers  enj^a^^ed  in  an  intlecisive  battle  at  short 
ranjie.  One  Japanese  destroyer  ^^•as  not  engaged.  One  re- 
l)ort(Ml  1  Icilled  and  'A  wounded,  not  seriously  hit.  Another  re- 
ported 1  killed  and  8  wounded,  2  guns  disabled  and  speed  re- 
duced. Another  reportetl  5  killed  and  2  wounded,  1  gun  dis- 
abled and  speed  reduced. 

On  March  10,  during  daylight,  4  Japanese  destroyer^  en- 
countered 2  Russian  craft,  1  of  which  was  sunk.  After  this 
action  1  Japanese  destroyer  reported  27  liits,  1  killed,  and  3 
wounded.  Another  6  hits,  1  killed,  and  1  Avounded.  Anotlier 
7  or  8  hits,  1  killed,  and  1  wounded.     The  fourth  nil. 

288.  Independent  control  of  guns. — l^>c("iuse  of  the  exces- 
sive luolion  of  the  destroyer  the  centralized  control  of  fire, 
[tract iced  in  larger  vessels,  and  which  is  desirable,  may  not 
always  he  jiossilile.  Training  should  permit  tlie  independent 
control  of  giuis  midi'i-  the  difliculties  imposed  by  the  poor  gun 
platform,  and  the  wide  separation  of  the  pieces. 

289.  Training'  for  individual  control  of  guns. — I'articular 
attention  should  be  given  to  the  training  of  gun  captains  and 
jiointers  in  these  ves.sels.  Spotters  must  be  trained  who  will 
be  competent  to  independently  control  the  tire  of  each  gun  (as 
is  the  case  in  larger  vessels,  sliould  such  become  necessary), 
at  the  short  distances  which  will  jtroliahly  become  tlie  battle 
ranges  with  guns. 

290.  Proficiency  of  pointers  trained  in  larger  vessels. — It 
may  be  that  pointers  of  secondary  guns  who  have  received 
traiinng  in  larger  vessels  will  not  be  well  qualified  to  direct 
the  pieces  in  smaller  craft  having  an  excessive  and  irregular 
motion.  There  should  be  no  hesitancy  in  replacing  such  quali- 
fied ])ointers  at  any  time  by  other  men  wliose  fitness  has  been 
demonstrated. 


GUNNERY  INSTRUCTIONS.  Ill 

SUBMARINES. 

Hints  and  Suggestions  for  a  Torpedo  Officer  of  a  Submarine. 

291.  Organization. — Tlio  fonipleniciil  of  the  pre-sent-day 
sulmiarine  Ls  18  to  20  hhmi,  of  wliom  0  are  ^^uuuer'.s  mates. 
Subuiaries  carry  from  2  to  4  torpedoes  and  should  have  1 
torpedo  man  for  each  tube.  These  torpedo  men  form  the  tor- 
pedo crew. 

292.  Torpedo  firing. — Supiiose  a  toi'pedo  has  just  been 
fued :  Close  the  tprpedo-tiil)e  cap,  bh)\v  or  pump  the  tube 
diy.  On  deck  rig  the  skids ;  in  the  torpedo  compartment, 
ri}i  the  cradle  to  the  torpedo  hatch.  For  holding  and  manipu- 
lalinj;  the  hitter,  small  doul)le  tackles  hooked  to  pad  eyes  are 
used.  Six  tackles,  four  to  liold  the  cradle  uii  and  two  to  move 
it  rorc-aiid-aft,  are  ^.jeueraily  employed.  In  some  vessels  the 
fcii'ward  end  of  tlie  cradlt>  is  held  i)y  an  iron  becket  into 
wliicli   a   1-t(iii   ditVerential   chain  purchase  is  hooked. 

293.  Recovering  torpedoes. — Special  care  should  be  given 
to  till"  e(iiupment  and  instruction  of  crews  of  boats  employed 
in  recovering  torpedoes.  The  equipment  shoulil  include  sufh- 
cient  buiiys  with  ancliors.  nose  and  tail  lines,  signal  flags,  pro- 
peller locks,  etc.  The  instructions  should  include  metho<l  of 
going  alongside  torpedo,  necessity  for  getting  nose  and  tail 
lin(>s  on  (|uickly,  necessity  for  keeping  boat's  propeller  clear 
of  torjiedo.  jioint  and  manner  of  ilelivery  alongside,  and  sig- 
nals to  l)e  employed.  Tlie  men  of  the  tiring  vessel  slioukl  be 
thoroughly  instructed  in  the  details  of  hoisting  out  the  torpedo 
and  striking  it  below. 

394.  To  load  and  fire  a  torpedo  submerged. — In  order  to 
put  the  torch  pot  into  the  exercise  head,  the  torpedo  must  be 
pulled  nearly  clear  of  the  tube.  After  the'torch  pot  has  been 
inserted  and  cutter '.screwed  on.  the  torpedo  may  be  pushed 
back  into  the  tube  until  only  the  immersion  chamber  and  after- 
body are  out.    In  this  position  the  torpedo  is  charged  and  the 


112  GUNNERY  INSTEUCTIONC. 

JHljustments  inaflo;  tlie  rap  is,  of  course,  closed  at  this  time. 
U'iien  ready.  I'ani  tlie  torpedo  lioiue,  one  man  holding  the  tube- 
trii)pinK  latrh  up  so  that  it  will  not  catcli  on  the  guide  stud. 
\N  hen  the  latter  brings  up  against  the  stop  the  torpedo  is  home 
and  seated.  In  order  to  he  assured  tliat  the  stop  will  lift 
readily  when  the  torpedo  is  tired,  tlie  whole  torpedo  should 
he  pulled  to  the  rear  about  one-eighth  of  an  inch.  Next  try 
out  the  impulse  valve  to  see  that  it  lifts.  Then  take  off  pro- 
l>eller  lock  and  close  the  tube  door.  There  are  several  schemes 
for  flooding  the  tubes.  Some  officers  obtain  the  trim  of  the 
vessel,  then  pump  the  tubes  full  from  the  water  in  the  for- 
ward trinuning  tank.  This  is  considered  the  best  way  where 
there  is  time  and  water  enough  in  the  foi-ward  ti-innning  tank 
!<■  till  tlie  tubes,  as  it  causes  very  little  change  in  the  weight 
and  trim  of  the  vessel.  Other  otticers  prefer  to  flood  the  tubes 
which  are  not  to  tire,  trim  down,  leaving  .-i  deficiency  of  about 
noo  pounds  in  the  forward  trimming  tank.  When  the  run  to- 
ward the  target  is  nearly  completed,  open  to  cap  and  flood 
I  lie  tube  to  be  tired.  If  accurately  done  this  is  a  very  good 
method,  but  there  is  always  a  chance  of  an  error  ))eing  made 
ill  tlie  proper  estimate  of  the  trim,  and  when  this  occurs  there 
is  ditticulty  in  handling  the  vessel.  Some  other  otticers  flood 
all  tubes  at  the  beginning  of  the  i-nn  and  obtain  a  perfect 
ti-im  at  the  start.  If  the  torpedo  is  absolutely  tight  this 
method  is  excellent,  but  the  torpedo  being  in  the  water  for  per- 
hajis  as  much  as  half  an  hour,  thei'e  is  .-iluays  a  chance  that 
it  will  leak.  .Tust  before  time  to  fire  put  a  pressure  of  from 
7r>  to  90  pounds  per  sqnai-e  inch  in  impulse  tank  and  see 
that  the  hundred-pound  tank  to  which  the  firing  line  connects 
has  100  iiounds  pressure  in  it.  In  the  I)  and  later  classes  the 
stop  bar  lifts  antoyiatically  from  the  guide  stud,  but  in  the  C 
class  and  earlier  ve.s.sels  the  stop  bar  Jias  to  be  lifted  by 
either  a  p(Hlal  or  a  hand  lever  just  before  firing. 

295.  Care  of  torpedoes. — Owing  to  the  very  limited  space 
for  handling   torpedoes  in   a   submarine,   they  are  necosxarily 


GUNNERY  INSTRUCTIONS.  H8 

subjecled  to  auicli  more  severe  usage  than  iu  other  vessels 
jind  therefore  need  more  care  in  order  to  obtain  tlie  best  re- 
siilts.  In  times  of  peace  only  half  the  full  complement  of  tor- 
pedoes is  carried  and  these  are  stowed  in  the  tubes.  The  tubes 
are  always  more  oi"  less  dam])  and  torpedoes  must  be  hauled 
nut,  \vi))ed  olT.  and  oiled  once  a  week,  and  before  firing  must 
be  comj)lete,l.v  brcjken  down  and  reassembbnl  in  perfect  condi- 
rion.  After  this  final  overlianl  a  torpedo  sliould  not  be  put  in 
water  until  ready  to  tire.  As  it  is  necessaiw  to  flood  all  tubes 
ill  order  to  open  the  f;\p  and  Are  any  one  tube,  tulies  that  are 
iiol  to  be  tired  sliould  be  empty.  A  subnuirine  making  an  at- 
lack  on  a  battleship  or  tleet  of  l)attlesliips  would  have  all 
lier  tul)e.s  loaded  with  torjiedoes  ready  to  tire  ami  would  liave 
the  remainder  of  her  torpedoes  ready  fo  load  into  the  tubes 
when  tli<'  first  were  fired.  This  operation  should  not  take  long 
and  would  be  accomplislavl  as  follows:  ('lose  the  cap.  blow 
the  water  out  of  the  tubes  tired,  ojx'n  the  dooi's  of  tliese  tulies, 
and  load  the  torpedoes. 

When  in  a  navy  yard  for  a  <'onsiderai)le  slay,  the  torpedoes 
should  be  stored  in  a  building  and,  before  leaving  the  yard, 
.1.,'lven  a  thorough  overhauling  and  test. 

296.  Care  of  g-yros. — The  interior  of  a  submarine  is  more  or 
less  damp  at  all  limes,  due  to  sweat,  and  s])ecial  cai'e  nuist  be 
taken  of  the  gyros  to  prevent  rusting  of  bearings.  The  follow- 
ing methods  have  been  used  with  good  residts: 

(a)  Fit  either  a  locker  or  a  tight  box  with  felt-covered 
liedestals  for  the  gj-ros  and  a  socket  for  a  5-candlepower  lamp. 
When  the  gyros  are  in  place,  turn  on  the  light  and  leave  the 
door  or  cover  open  slightly  for  an  hour  or  two.  until  the  air 
in  the  locker  or  box  is  dried,  then  close  the  cover  and  the 
gyrfis  will  be  kept  dry. 

{b)  A  copper  tank  is  made  and  fitted  with  pedestals  for 
gyros  and  then  filled  with  sperm  oil,  in  which  the  gyros  are 
kept  completely  immersed.  Before  using,  the  oil  must  be 
34776—18 8 


114  GUNNERY  INSTRUCTIONS. 

blown  off  the  gyros  with  dry  compressed  air.  Twice  a  year 
the  gyros  should  be  completely  disassembled  and  all  bearings 
cleaned,  those  in  poor  condition  renewed,  and  all  given  a  light 
oiling  of  wiitch  oil.  Before  beginning  torpedo  work  the  gj-ros 
should  bo  adjusted  in  the  stand.  If  opportunity  offers,  it  is 
desirable,  to  check  the  adjustment  by  running  the  torpedoes 
over  a  range.  A  steady  platform  for  adjusting  in  tlie  stand 
may  be  obtained  quickly  by  submerging  to  the  bottom. 

297.  Tests. — The  firing  valves  and  tube  mechanism  should 
be  tested  frequently,  and  always  before  firing,  and  should  be 
thoroughly  overhauled  while  at  a  navv  vard. 


CH  AFTER  12. 
NOTES  ON  TARGET  PRACTICE. 

298.  Preparations  for  target  practice. — Target  practice  is 
ii  test  of  i>revious  trniiiinij;  and  prei»aratioii  for  i)atllo.  and 
when  the  time  for  practice  arrives  it  is  too  late  to  correct 
n(>j;lecte(l  features.  If  tlie  Iraininp;  and  preparations  Imve 
l)('(>n  tliorougli.  everytlnn.u'  sliould  run  sniootlily  and  all  cas- 
ualties that  occui-  will  ho  handled  witlioul   confusion. 

299.  Suggestions  for  target  practice. — Following  ai'e  cer- 
tain .suggestions  for  target  practice — .some  .apply  to  elemen- 
tary and  others  to  battle  practices,  some  to  turret  and  others 
lo  bri>adside  guns. 

(a)  MISCELLANEOUS. 

1.  A  smart  iit'rl'oi'mance  is  generally  a  good  performance. 
Loss  of  time  and  a  carelessness  with  details  incidental  to  the 
practice  militate  against  interest  in  the  exercise  and  a  satis- 
factory result  thereof. 

2.  Arrange  and  publish  a  complete  sequence  of  the  practice. 
See  that  safety  precautions,  rules,  and  the  orders  for  the  prac- 
tice are  understood  by  all  concerned. 

3.  Be  sure  that  pointers  understand  the  theory  of  and  i)rac- 
tical  necessity  for  laying  pieces  accurately. 

4.  Tiike  precaiitions  to  prevent  noise  and  crowding  in  neigli- 
borliood  of  guns ;  rope  off  space  if  necessary. 

5.  Sweep  up  decks  about  breech  of  guns. 

115 


lie  GUNNERY  INSTRUCTIONS. 

6.  Paint  a  circle  around  l^roadside  guns  at  a  distance  from 
iireecli  about  0  inches  greater  tlian  the  recoil  as  a  guide  to  the 
crew. 

7.  Be  prepared  for  any  casualties  tliat  may  occtn-. 

8.  Designate  and  man  substitute  guns  for  each  run. 

9.  Arrang(^  to  care  for  observers  and  umpires  that  visit  ship. 

(b)  RANGE,  TARGETS,  ETC. 

1.  Measure  and  check  size  of  target  screens. 

2.  Give  full  instructions  to  repair  party. 

3.  Arrange  system  of  signals  with  repair  boat. 

4.  Provide  ample  spare  target  gear. 

5.  See  target  screens  correctly  set. 

6.  Check  speed  and  cour.se  of  target. 

7.  In  coming  on  range  be  sure  that  ship  has  attained  stand- 
ard speed  and  is  steady  on  course  before  the  firing  point  is 
reached. 

(c)  FIRING  CONNECTIONS. 

1.  Thoroughly  test  all  connections.  See  that  every  connec- 
tion in  the  circuit  is  clean  and  secure  and  thoroughly  tape 
them  all.    Use  ether  or  alcohol  in  cleaning  connections. 

2.  Overhaul  firing  keys.  ( Instead  of  using  a  transfer  switch 
many  officers  prefer  to  use  the  pistol  grip  on  the  motor  gener- 
ator circuit  and  a  push  button  secured  to  the  side  of  the  pistol 
grip  in  the  battery  circuit.) 

3.  Overhaul,  clean,  and  oil  the  lock.  Use  oil  sparingly 
around  firing  jiin  and  on  face  of  wedge. 

4.  Clean  and  examine  firing  pin,  and  vulcanite  bushings  in 
electric  firing  locks. 

5.  Examine  all  wiring  and  insulation  in  firing  circuits. 

6.  See  that  circuit  will  not  be  fouled  or  damaged  by  the 
recoil  of  the  gun.  If  necessary  trice  up  bight  of  wire  by 
moderately  strong  spring  to  some  point  above  gun. 


GUNNERY  INSTRUCTIONS.  117 

7.  Test  firing  circuits  witli  volt  and  ammeter  and  finally 
with  primers. 

8.  A  missfire  should  not  occur,  hut  anticipate  and  be  pre- 
1  tared  for  such  a  contingency. 

(d)  AMMUNITION. 

J.  Clean,  brighten,  and  test  all  primers. 

2.  Clean  all  shell  and  cartridge  cases. 

3.  Examine  powder  bags  and  repair  any  that  may  be  dam- 
aged. (Place  paper  in  eliamber  of  gun  and  then  try  a  powder 
charge  to  be  sure  that  the  index  to  be  used  is  in  all  respects 
satisfactory.  See  lacing  is  tight.  Be  sure  that  this  charge  is 
fired  on  the  practice.) 

4.  AN'eigli  shell  and  paint  noses  as  directed;  wet  paint  is 
slippery  and  may  give  trouble  to  and  worry  shellmen  and 
ranmiermen. 

5.  Watch  magazine  temperatures  carefully  and  have  all 
powder  temperatures  the  same  when  firing  takes  place.  Have 
regard  for  powder  temperatures  if  ammunition  is  to  be  left 
long  on  declv. 

6.  Test  fixed  ammunition  by  trying  each  cartridge  in  gun, 
fh-st  removing  firing  pin. 

7.  lilxamine  carefully  for  sunken  primers  (fixed  ammuni- 
tion). 

8.  Be  sure  that  charges  will  be  loaded  with  ignition  ends  to 
(he  rear. 

1).  See  shell  well  seated  and  secure  in  cases  (fixed  ammuni- 
tion). 

](>.  S(^('  that  shell  bands  are  not  burned  and  arrange  to 
have  slu'll  uniformly  and  well  seated  in  gun  (separate  am- 
nmnition). 

11.  Lay  out  shell  and  charges  in  a  way  most  convenient  for 
loaders. 


118  GUNNERY  INSTRUCTIONS, 

(e)  MOUNT  AND  GUN. 

1.  Eliminate  lost  motion  and  see  mount  in  perfect  worliing 
condition. 

2.  See  screw  box  free  of  burrs. 

8.  Overliaul  and  adjust  gas  checl<  pad. 

4.  Overliaul,  clean,  and  oil  the  plug,  and  all  features  of  the 
plug  operating  mechanism. 

5.  See  primer  vent  clean  and  primer  seat  clean  and  free  of 
grit  or  dirt. 

G.  Set  up  friction  cones  in  training  gear. 

7.  See  electric-controller  fingers  smooth,  and  give  same  a 
light  coating  of  vaseline. 

8.  Examine  gas-expelling  devices,  blow  through  to  get  water 
and  any  possible  dirt  out  of  system,  and  see  nozzles  clear. 

9.  Examine  and  be  sure  that  every  nut,  bolt,  gland,  etc., 
about  the  mount  is  in  place  and  properly  adjusted. 

10.  Fill  the  i-ecoil  cylinders  and  see  hlling  plugs  in  and  well 
set  down. 

(f)   SIGHTS. 

1.  Be  sure  that  guns  are  correctly  boresighted  and  that 
there  is  no  parallax  in  telescopes,  or  parallax  in  the  boresight- 
ing  telescopes  when  the  sight  adjustment  is  made. 

2.  Be  sure  that  sight  scales  are  properly  illuminated. 

3.  Be  sure  that  sight  setting  will  be  accurately  and  expe- 
ditiously accomplished. 

4.  See  strips  properly  secure  and  be  sure  that  proper  strip 
is  in  place  for  the  charge  and  type  of  shell  that  are  employed. 
Be  prepared  to  wipe  off  sight  lenses. 

5.  See  that  all  clamps,  etc.,  are  .secure.  Set  up  (aul  befoi-e 
boresighting.  and  don't  touch  again  before  firing. 

G.  Have  ray  lilters  provided  and  ready  for  use. 

7.  When  at  navy  yard  test  sights  for  parallelism,  drift,  de- 
flection, and  adjustment  with  the  guns,  using  battens,  and 
eliminate  lost  motion. 


GUNNERY  INSTRUCTIONS.  119 

(g)  FIRE  CONTROL. 

1.  Arrange  a  (.leliiiile  plan  for  tire  conlrol,  including  firing 
of  ranging  shots,  and  salvos,  and  for  individual  turret  control. 

2.  Prepare  and  check  the  necessary  range  data,  ballistic  and 
s]»()tting  corrections,  carefully. 

;{.  Test  all  iire-cuntrol   circuits,  tolephones,  elc. 

4.  Be  sure  that  there  will  be  no  pt)ssibility  of  u  correction 
failing  to  reach  or  to  appear  on  the  sight  of  a  firing  gun  be- 
fore the  firing  takes  place. 

o.  Adjust  range  finders. 

6.  If  trial  shots  are  allowed,  get  all  data  possible,  including 
record  of  ability  of  turret  officers  to  spot  through  periscopes. 

7.  See  that  suitable  arrangements  are  made  for  spotter, 
searchlight-control  men,  those  stationed  to  give  salvo  signals, 
etc. 

8.  Be  assured  that  point  of  aim  is  understood  by  all 
pointers. 

300.  Frequent  causes  of  poor  scores. — Reports  show  that 
scores  are  most  frequently  reduced  by  the  following  causes: 

(«)   Slow  and  inaccurate  sight  setting. 

(h)  Slow  and  uncertain  communication  of  the  spotter's  ob- 
servations to  the  firing  gun. 

(c)  Too  much  spotting.  With  a  correct  rate  of  change  of 
range  after  the  spotter  has  brought  the  shots  on  the  target  they 
shouhl  automatically  stay  there.  There  should  be  no  necessity 
for  spotting  other  than  the  first  shot  of  a  string. 

{d)   Poor  spotting. 

rmmediatehi  alter  practice  check  up  sights,  and  search  out 
the  reason  for  any  failure  of  material  or  unrntinfartorii  per- 
formance. 


CHAPTER  13. 
ALIGNMENT  OF  SIGHTS  AND  BOEE  SIGHTING. 

301.  Alignment  of  sights — Necessity  for  correct  align- 
ment.— Sights  shouUl  always  be  in  perfect  alignment  with  the 
gun;  that  is,  the  axis  of  colliniation  of  the  telescope  should, 
when  set  at  O  and  bore  sighted  at  infinity,  be  parallel  to  the 
longitudinal  axis  of  the  gun  at  all  positions  of  elevation  and 
depressitin.  In  order  to  obtain  such  perfect  alignment  a  high 
tlegree  of  excellence  of  sight  installation  is  necessary  and  this 
alignment  must  be  checked  from  time  to  time  and  adjust- 
ments must  be  made  as  required.  The  installation  and  align- 
ment of  sights  requires  expert  mechanical  workmanship  and 
a  thoroiigh  knowledge  of  the  sight  installation  and  it  is  not 
considei'ed  advisable  to  attempt  to  realign  sights,  which  are 
out  of  adjustment,  except  in  case  of  absolute  necessity,  with 
the  means  available  aboard  ship.  However,  battery  officers 
should  know  how  to  check  the  sight  adjustments  so  as  to  be 
able  to  locate  the  source  of  any  improper  alignment  and  the 
resulting  effects.  Apparently  inaccurate  shooting,  inconsist- 
ent dispersion,  and  other  faults,  sometimes  attributed  to  poor 
gun  pointing,  may  be  caused  by  improper  alignment  of  sights 
and  by  inaccurate  bore  sighting.  If  the  sights  are  out  of  line, 
bore  sighting  will  not  correct  the  difficulty  and  with  such  the 
case,  it  is  impossible  to  bore  sight  with  accuracy. 

302.  Causes  of  error. — Any  of  the  following  causes  may 
affect  sight  alignment: 

(o)  Roller  path  not  level. 
120 


GUNNERY  INSTRUCTIONS.  121 

(b)  Guns  not  properly  adjusted  on  the  kuil'e  edges,  so  that 
the  trunnion  axis  is  not  parallel  to  the  plane  of  the  roller  path. 

(c)  Rigid  parts  of  sight  mount  may  be  improperly  installed. 

(d)  Working  i)arts  of  sight  may  be  badly  worn  causing  lost 
motion  in  some  places  and  binding  in  others. 

Tlie  battery  officer  is  not  concerned  witli  (a)  for  that  is  a 
defect  which  can  not  l)e  readily  ascertained,  nor  can  it  be 
easily  corrected.  Naturally,  the  amount  of  error  depends 
upon  the  angle  of  inclination  of  the  roller  path,  but  whatever 
this  angle  may  be,  the  sight  alignment  will  be  affected  but 
little,  if  the  trunnion  axis  is  parallel  to  the  roller  path  plane 
at  any  point  in  train.  With  guns  independently  pointed  the 
error  due  to.  («)  can  be  neglected. 

303.  Checking'  broadside  sig'hts. — For  checking  broadside 
siglits  the  ship  must  be  placed  in  dry-dock.  If  yoke  sights  are 
once  properly  installed,  and  are  cared  for,  improper  alignment 
will  result  from  only  the  natural  wear  of  working  parts,  and 
this  cause  of  error  will  be  very  slight. 

304.  Checking'  turret  sights. — Tlie  following  procedures  are 
reconnnended  fur  checking  the  alignment  of  turret  sights. 
(See  Ordnance  Pamphlet  No.  18  of  September,  1907 — Notes  on 
installation  and  tests  of  turrets,  guns,  and  sights.) 

305.  Distant  object  method. — This  method  can  be  conven- 
iently aeconiplislied  in  dry  tlock  as  follows:  Adjust  both  gun- 
sight  telescope  and  bore  sight  on  a  distant  object.  Elevate  the 
sight  to  extreme  range  (without  touching  deflection)  and  then 
elevate  the  gun  until  the  horizontal  wire  of  the  sight  is  again 
on  the  object  observed.  If  the  sight  is  in  correct  adjustment 
the  vertical  wire  will  also  be  on  the  object.  If  this  is  not  the 
case,  move  in  deflection  until  it  is  on  and  note  the  amount  of 
knots  error.  By  referring  t(»  the  range  tables  the  angular 
error  can  be  obtained.  If  the  error  is  one-half  a  knot  or  less 
it  may  be  considered  as  satisfactory. 

306.  Batten  method — (o)  Train  and  secure  turret. — The 
turret  should  be  trained  to  its  securing  position  either  forward 


122  GUNNERY  INSTRUCTIONS. 

or  aft  where  it  cau  be  secured  for  several  days  while  the 
sights  are  being  checked. 

( b )  Erect  battens. — Procure  five  good  pine  boards  1  inch  or 
li  inches  thick  and  14  to  16  feet  long,  planed  on  one  side. 
Erect  these  boards  as  far  away  from  the  sights  as  necessary 
for  clear  focus,  with  the  smooth  side  of  the  boards  facing  the 
turret.  The  five  l)oards  must  be  parallel  and  in  the  same 
Itlane  so  that  tlie  axis  of  each  telescope  and  gun  prolonged 
will  intersect  the  center  of  the  board  facing  it.  The  boards 
must  be  well  braced  so  that  the  completed  structure  will  be 
absolutely  rigid.  Extreme  care  must  be  taken  to  insure  that 
the  face  of  the  batten  boards  is  parallel  to  the  muzzles  of  the 
guns  when  they  are  level — in  other  words,  parallel  to  a  ver- 
tical plane  passed  through  the  axis  of  the  trunnions.  A  step- 
ladder  must  be  made  so  that  work  cau  be  done  on  the  struc- 
ture without  moiniting  the  battens,  for  to  do  so  will  cause  the 
structure  to  change  its  shape  and  cause  error. 

(c")  Adjustment  of  knife  edges. — Drawings  in  the  posses- 
sion of  the  gunnery  officer  show  the  amount  of  necessary 
clearance  around  the  trunnions  when  the  guns  are  on  their 
knife  edges,  and  the  knife  edges  must  be  adjusted  to  this 
clearance.  The  trunnion  should  be  just  lifted  off  its  seat  and 
most  of  tbe  clearance  should  be  left  on  the  upper  side  of  the 
trunnion.  Some  mounts  are  fitted  with  micrometer  gauges 
to  measure  this  clearance,  but  with  others  it  will  be  necessary 
to  use  feelers.  Before  adjusting  trunnion  bearings  the  guns 
should  be  approximately  level. 

((7)  Level  guns. — The  guns  must  be  laid  acciu-ately  level. 
To  do  this,  place  the  quadrant  level  on  the  gun  or  on  the 
yoke  in  rear  of  the  slide.     Use  hand  elevating  gear. 

(e)  Set  range  strips.— See  that  all  range  strips  and  deflec- 
tion drums  are  tightly  secured  and  set  all  sights  accurately 
at  zero  range  and  deflection. 

(/)  Adjust  telescope. — Telescopes  must  be  clean,  free  from 
parallax,   and    well   secured    in   their   holders   and    focussed. 


GUNNERY  INSTRUCTIONS.  123 

Cross  wires  must  be  exactly  in  place  so  that  the  vertical  wire 
is  actually  vei'tical. 

(g)  Adjust  bore  sights. — Put  in  the  bore-sight  telescopes 
and  have  them  well  secured.  As  the  bore  sights  will  be  in 
place  for  some  time,  it  is  advisable  to  entirely  remove  the 
breech  plug,  rather  than  to  lash  it  back  on  account  of  the  sus- 
tained weight  of  the  plug  on  the  hiuge  pin,  which  may  affect 
the  alignment  of  the  rotating  and  swinging  mechanism.  Focus 
the  bore-sight  telescope  on  the  batten  boards  after  removing 
parallax.  Put  muzzle  disks  in  place  and  adjust  cross  wires 
of  bore-sight  telescopes  so  as  to  split  the  central  hole  of  the 
disk.     Remove  nmzzle  disks. 

(h)  Spot  points  on  battens. — With  guns  level  and  using  the 
bore-sight  telescopes,  spot  points  on  batten  boards  ami  through 
these  points  stre,tch  a  small  strong  waxed  line  horizontally 
as  shown  on  Figure  I.  Likewise  with  pointer's  and  trainer's 
telescopes  spot  points  (/,  b,  and  c,  respectively.  Figure  I. 
Through  these  points  a,  b,  and  c  erect  perpendiculars,  using 
using  strong  waxed  cord.  These  lines  should  be  parallel 
and  the  distance  x  should  be  equal  to  x',  and  y  should  be 
equal  to  ?/'.  Now  if  there  be  no  turret  structural  defect  and 
the  guns  are  properly  adjusted  on  the  knife  edges,  they  should 
elevate,  in  the  vertical  plane  and  the  vertical  wire  of  the  bore- 
sight  telescopes  should  split  the  lines  a  a'.  Likewise  if  the 
sights  are  in  perfect  alignment  with  the  guns,  the  vertical 
wire  of  the  telescopes  should  split  the  lines  b  b'  and  c  c' 
at  all  degrees  of  elevation. 

(i)  Settling'  of  deck  lugs.— With  a  ship  that  has  been  in 
commission  for  some  time  and  has  been  through  numerous 
targe,t  practices,  there  is  a  certain  inevitable  settling  of  the 
deck  lugs  and  turret  structure.  Though  the  guns  may  be 
properly  adjusted  on  their  knife  edges,  they  may  not  elevate 
exactly  in  the  vertical  plane.  After  erecting  the  lines  as 
mentioned  above,  elejvate  the  guns,  having  an  observer  sta- 
tioned at  the  bore  sight;  the  displacement  will  at  once  be 


124 


eUWNERY  INSTRUCTIONS. 


seen.  After  ascertaining  that  this  condition  exists,  lay  the 
guns  level  and  again  .spot  the  points  a,  b,  and  c.  Elevate 
the  guns  to  a  point  near  the  top  of  the  hatte^i  boards  and  spot 


Poinler's    sighl   Line. 


Left    gun    line. 


1 p 


Trdtners    sight    Line. 

Right    gun   line 


Povnlcr's    stqht    Itne.. 
a-- 1-| 2 


tlie  points  a',  h',  and  c' ;  through  a  a',  h  h' ,  and  c  a'  stretch 
tight  lines  and  proceed  with  the  checking  of  the  alignment 
of  the  sights. 

(/)   Check  results. — The  guns  should  be  elevated  and  de- 
pressed several  times  while  the  bore  sight  and  sight  telescope 


GUNNERY  INSTRUCTIONS.  125 

are  checked  over  the  lines  to  insure  that  they  are  correctly 
drawn.  IMciisure  the  (lislance  hetwoon  eacli  run's  gun  line 
and  .sight  lines,  (-)n  the  battens  this  should  be  the  same  at  toi) 
and  bottom  ;  if  nof.  sights  are  not  aligned  with  guu.s. 

307.  Lag  in  range. — To  te.st  for  lag  in  range,  due  to  binding 
and  sitriugiiig  of  jiarls  and  to  lost  motion,  set  the  sights  accu- 
rately at  any  range,  say  ."i.OOO  yards,  and  spot  a  mark  on  the 
batten  board  as  shown  a1  (/.  Run  the  sight  up  to  extreme 
range  and  back  to  5,000  yards  and  see  if  the  cro.ss  wires  split 
the  mark  fl :  if  there  is  lag.  a  new  point  (/'  will  be  found. 
Kun  the  sights  down  to  zero  and  back  to  ."i,000  yards  as  a 
further  test.     (See  art.  305.) 

308.  Tabulation  of  results. — The  following  information  is 
thus  ascertained  when  checking  sight  alignment  and  should 
be  carefully  tabidated  and  recorded  : 

id)  Convergence  or  divergence  of  guns. 

(h)   Perpendicularity  of  plane  of  elevation  of  guns. 

(c)   Sight  alignment. 

((/)   Lag  of  sights  in  range. 

309.  Parallelism. — Tram  breech  and  nnizzle  at  level  and  at 
elevation  of  5°  to  a.scertain  the  parallelism  of  the  guns.  It 
may  be  noted  that  exact  parallelism  is  not  essential,  though 
desiral)le.  A  convergence  or  slight  divergence  at  high  ranges 
will  not  produce  inaccurate  results.  It  may  not  be  possible 
to  bring  the  guns  exactly  parallel  or  to  any  required  degree 
of  convergence,  by  trunnion  bearing  adjustment.  This  can  be 
jiccomplished  to  a  small  extent,  however,  and  once  accom- 
plished the  adjustment  should  never  be  changed  without  im- 
mediately realigning  the  sights. 

310.  Adjustment  to  be  made  by  yard  force. — Sight  align- 
ment should  not  be  attempted  by  the  ship's  force.  The  results 
of  checking  should  be  carefully  recorded  and  forwarded  to  the 
Bureau  of  Ordnance  for  action,  with  a  request  that  proper  ad- 
justments be  made,  if  such  appear  necessary. 


126  GUNNERY  INSTRUCTIONS. 

NOTES  ON  BORE  SIGHTING. 

311.  Definition. — Bore  ."lighting  is  the  adjusting  of  gun 
sights,  wlien  the  sight  bar  is  set  for  zero  range  and  the 
iiziniuth  licad  for  zero  deflection,  so  that  the  lines  of  sight  of 
the  pointing  telescopes  will  intersect  the  geometrical  axis  of 
the  bore  produced  at  the  mean  range  at  which  it  is  expected  to 
fire.  Guns  that  are  correctly  bore  sighted  for  ranges  of  10,000 
yards  are,  for  the  purposes  of  battle,  bore  sighted  for  battle 
ranges. 

312.  Why  necessary. — It  is  necessary  because  the  line  of 
sight  does  not  coincide  with  the  axis  of  the  bore  of  a  gun. 

313.  Errors  due  to  sights  not  being  in  horizontal  plane 
with  axis  of  bore. — Fii-st,  consider  the  error  due  to  the  sights 
being  elevated  above  the  axis  of  the  bore.  Figures  Il(ffl)  and 
Til  (ft).  It  will  be  noticed  that  when  the  bore  is  centered 
upon  a  point  Y  at  the  target  the  lines  of  sight  of  the  pointing 
telescopes  will  intersect  the  target  in  a  liorizontal  plane 
through  the  point  X.  a  distance  X-Y  above  Y,  equal  to  the 
amount  that  the  center  line  of  the  telescopes  are  above  the 
center  line  of  the  bore. 

If  the  distance  from  the  gun  to  the  target  is,  for  example 
2,.')00  yards,  the  sight  bar  is  set  for  2.500  yards,  and  the  gun 


GUNNERY  INSTEUCTIONS. 


127 


> 


128  GUNNERY  INSTRUCTIONS. 

elevated  so  that  the  horizontal  wires  of  the  pointing  telescopes 
are  on  the  horizontal  line  through  X,  a  shot  Avould  hit  the  tar- 
get at  Y,  not  X. 

However,  if  the  gun  is  centei'ed  on  the  point  Y  and  the  sight 
Itar  raise<l  or  lowered  until  the  wires  of  the  telescopes  are  on 
the  horizontal  line  through  Y',  the  lines  of  sight  will  have  been 
depressed  through  an  angle  X,  and  the  sight  bar  raise<l 
tiu'ough  an  arc  A-B.  If  the  sight  strip  is  now  loosened  and 
slid  down  until  the  zei-o  graduation  is  in  line  with  the  pointer 
on  the  sight-bar  bracket,  without  moving  the  sight  bar  itself, 
ii  shot  firefl  under  the  same  conditions  as  above  would  pierce 
(he  target  at  the  same  point  at  which  the  wires  of  the  point- 
ing telescope  rested. 

Without  altering  any  of  the  above  adjustments  or  condi- 
tions, except  lowering  the  sight  bar  to  read  zero  and  moving 
the  target  out  on  its  same  bearing  until  fj.OOO  .vai'ds  from  the 
gun,  center  the  boi-e  of  the  gun  ujioii  the  horizontal  line 
through  Y,  and  it  will  be  fomid  that  the  horizontal  wires  of 
the  telescopes  will  lay  upon  a  horizontal  line  through  Z,  a 
distance  X-Y"  below  Y,  showing  that  an  exact  coincidence  of 
llie  horizontal  wires  and  the  center  of  the  hole  made  by  the 
shot  can  only  be  possii)le  when  the  gun  is  fired  at  the  exact 
range  at  which  the  sights  have  been  adjusted. 

Tliis  angular  error  in  the  vertical  plane  we  find  to  be  great- 
est with  turret  parallel  motion  sights  and  least  with  the 
l>roadside  periscopic  sight  mounts  and  the  periscopic  sights 
for  turrets  wliich  are  attached  to  the  trunnions  of  the  guns. 

314.  Errors  due  to  sights  not  being-  in  vertical  plane  of 
axis  of  bore. — Sighting  errors  due  to  the  lines  of  .sight  of  the 
I)()inting  and  training  telescopes  not  being  in  the  same  verti- 
cal plane  as  the  axis  of  the  bore  is  shown  in  Figures  II  (6) 
and  III  (b). 

In  sight  mounts  Avhich  contain  both  the  elevating  and  train- 
ing telescopes  the  sighting  error  is  the  same  for  both  tele- 
scopes, a.s.suming  that  the  lines  of  sight  are  parallel  to  the 


GUNNERY  INSTRUCTIONS.    . 


129 


II 


/. 


34776—18 9 


Fia.  II  (6). 


130  GUNNERY  INSTRUCTIONS. 

bore.  Therefore,  iu  order  that  the  lines  of  sight  be  made 
to  lay  in  the  same  vertical  plane  at  the  target  as  does  the 
geometrical  axis  of  the  bore  produced,  it  will  be  necessai-y  to 
swing  each  telescope  through  a  small  horizontal  angle  a. 

315.  Uniform  conditions  when  bore  sighting.— Heat  af- 
fects the  droop  of  guns  to  some  extent,  and  the  atmospheric 
conditions  vary  at  different  times  during  the  day.  All  guns 
of  a  battery  should  be  bore  sighted  under  similar  conditions 
of  temperature,  light,  etc.,  hence  at  as  nearly  as  possible  the 
same  time  of  the  day. 

316.  Turret  trainer's  sights. — In  turret  sight  mounts  where 
the  training  telescope  is  not  connected  with  the  elevating 
telescope,  it  is  impossible  to  have  the  line  of  sight  of  the 
training  telescope  lie  in  the  same  vertical  plane  at  the  target 
as  does  the  elevating  telescopes,  except  where  the  target  is 
at  such  a  great  distance  that  the  axis  of  the  bore  and  the 
lines  of  sight,  if  all  parallel  to  one  another,  appear  to  meet 
and  the  horizontal  angles  through  which  the  telescope  should 
be  swung  are  so  small  that  the  azimuth  heads  can  not  be 
moved  a  sufliciently  small  amount  to  correct  them. 

If  the  target  is  to  be  at  a  short  range,  say  2,500  yards,  and 
the  turret  sights  are  to  be  adjusted  in  azimuth,  the  sights  may 
be  adjusted  to  suit  conditions  as  follows : 

Make  each  elevating  pointer's  telescopic  line  of  sight  inter- 
sect the  geometrical  axis  of  the  bore  of  its  gun  at  the  target 
for  zero'  setting  of  the  range  and  deflection  scales,  as  shown  in 
Figures  IV  (a)  and  (6).  Then  have  the  line  of  sight  of  the 
training  telescope  intersect  the  plane  of  the  tai'get  midway 
between  C  and  D.  It  would  be  necessary  for  the  training 
pointer  to  have  a  point  of  aim  to  the  right  of  the  bull's-eye 
for  the  left  gun,  and  to  the  left  of  the  bull's-eye  for  the  right 
•gun,  if  guns  are  fired  independently  and  the  target  is  not  of 
suflicient  length  to  allow  for  the  distance  between  the  guns. 

317.  Preparation  of  bore  sights. — The  ship  being  at  anchor, 
where  there  is  no  motion,  anchors  a  raft  or  boat  parallel  to 


GUNNERY  INSTRUCTIONS.  131 

its  own  heading,  and  iu  it  erects  a  screen,  preferably  white 
with  black  horizontal  and  vertical  lines.  This  screen  should 
be  spread  as  taut  as  possible,  so  that  the  top  and  side  edges 
will  be  as  nearly  horizontal  and  vertical,  respectively,  as 
can  be. 

If  circumstances  do  not  permit  using  a  boat,  then  some 
prominent  object,  either  ashpre  or  afloat  and  at  the  required 
distance,  may  be  utilized.  Bore  sightiqg  at  night  may  be 
accomplished  by  using  a  searchlight  to  illuminate  the  target 
if  the  range  is  not  too  great. 

If  the  telescopes  have  been  removed,  before  returning  them 
carefully  wipe  the  telescope  holders  to  remove  all  grit  from 
the  bearing  surfaces. 

Iu  setting  up  the  securing  nuts  on  the  holders,  set  up  grad- 
ually upon  each  one  in  succession.  Never  set  one  screw  or 
bolt  of  a  bearing  up  taut  and  all  the  way  home  independently 
of  the  others.  In  setting  up,  never  use  any  wrench  other  than 
the  one  supplied  with  the  sight  for  this  purpose,  as  the  jaws 
of  this  wrench  will  give  before  the  threads  on  the  nuts  will 
strip. 

After  the  telescope  is  in  place  the  sight  bar  and  the  deflec- 
tion drum  are  moved  through  a  complete  throw  to  insure 
there  being  no  freezing  of  parts. 

The  breech  plug  is  lashed  back  to  prevent  its  accidently  be- 
ing closed  against  the  telescope  in  the  breech  disk.  (This  is 
mandatory. ) 

The  breech  disk  is  fastened  or  .screwed  into  the  breech,  and 
the  bore-sight  telescope  secured  in  place,  all  parallax  being 
removed.  This  telescope  is  focused  after  it  has  been  screwed 
and  clamped  in  place.  When  in  focus  the  hole  in  the  nmzzle 
disk  will  appear  blurred.  The  muzzle  disk  (c')  Figure  II  (a) 
has  a  hole  about  one-sixteenth  of  an  inch  in  diameter  in  its 
center.  Only  the  central  hole  should  be  used  for  centering 
the  bore-sight  telescope,  the  other  four  holes  in  the  muzzle 
disk  are  for  lighting  purposes  only.    Before  bore  sighting,  the 


GUNNERY  INSTRUCTIONS. 


GUNNERY  INSTRUCTIONS.  133 

horizoutal  wire  of  .ill  telescopes  slioukl  be  adjusted  on  tlie 
horizon  or  auy  distant  level  object.  In  order  to  prevent  in- 
jury or  loss  in  centering  it.  a  lanyard  sliouhl  be  made  fast 
to  the  dislv  and  the  end  passed  in  on  dock  or  properly  se- 
cured. 

To  adjust  tlu'  breech  telescope,  there  are  four  adjusting- 
screws  on  the  holder  for  the"  telescope  so  that  by  coming  up 
on  one  and  setting  up  on  the  one  diametrically  opposite,  the 
telescope  may  be  moved  about  until  the  intersection  of  the 
cress  wires  appears  in  the  small  hole  in  the  center  of  the 
muzzle  disk. 

These  adjusting  screws  nuist  not  be  set  ui»  so  hard  as  to 
strain  or  distort  the  telescope,  and  only  sufficiently  to  hold 
the  telescope  propei-ly  in  place.  In  looking  through  the  bore- 
sight  telescope,  care  nuist  be  taken  not  to  disturb  the  adjust- 
ment by  touching  it  with  the  hand,  cap  visor,  or  forehead. 

In  case  there  is  not  sufficient  light  to  see  the  cross  wires  of 
the  breech  telescope  when  the  muzzle  disk  is  in,  a  small  port- 
able may  be  held  near  the  muzzle. 

The  muzzle  disk  is  rotated  through  180°  as  a  check  as  to 
whether  or  not  the  intersection  of  the  cross  wires  is  centered. 
If  it  is  found  not  to  be,  the  fault  is  probably  due  to  the  muzzle 
disk  not  having  been  placed  squarely  in  the  muzzle. 

318.  Information  in  regard  to  the  bore-sight  telescope. — 
On  pages  4  and  5  illustrated  by  plate  2  of  Ordnance  pamphlet 
No.  345  are  a  few  words  regarding  the  bore-sight  telescope. 
On  pages  7,  8,  9,  10,  and  11  are  some  general  notes  on  the  care 
and  handling  and  cleaning  of  telescopes  which  apply  to  a 
certain  extent  to  the  bore-sight  telescopes.  There  are  two 
sources  of  error  in  bore-sight  telescopes  which,  it  is  believed, 
are  very  frequent,  and  are  caused  by  disassembling  the  tele- 
scopes for  cleaning.  One  of  these  errors  is  due  to  the  fact 
that  after  cleaning  the  cross-line  diaphragm  and  replacing  it, 
it  Is  not  returned  to  its  correct  position,  resulting  in  a  parallax, 
which  causes  an  increasing  error  depending  upon  the  distance 


134  GUNNERY  INSTRUCTIONS. 

of  the  cross-line  diapliragm  from  the  focal  or  image  plane  of 
the  objective.  All  telescopes,  if  disassembled  for  cleaning, 
upon  reassembling  should  be  tested  for  this  error  by  accurately 
focusing  the  telescope  upon  a  distant  object  and  moving  the 
cross  lines  back  and  forth  until  no  parallax  remains.  This,  of 
course,  will  have  to  be  done  before  the  breech  piece  socket  (57) 
and  the  outside  adjusting  tube  (69)  are  replaced  on  the  tele- 
scope. 

The  second  error  is  caused  by  the  fact  that  in  reassembling, 
the  cross-line  intersection  is  not  accurately  placed  in  the  line  of 
collimation  of  the  telescope.  To  overcome  this  error,  after  the 
parallax  has  been  eliminated  as  indicated  above,  the  telescope 
should  be  placed  in  Y  bearings  and  rotated.  A  turned  surface 
is  provided  near  the  two  ends  of  the  telescope  tube  for  this 
purpose.  The  telescope  should  be  sighted  upon  a  distant 
object,  and  it  will  be  found  that  when  the  telescope  is  rotated 
in  the  Y's  that  the  cross  lines  will  shift  upon  the  distant  ob- 
ject. The  cross  lines  should  be  accurately  centered  by  means 
of  the  four  cross-line  adjusting  screws  (27)  until  the  cross- 
line  intersection  does  not  shift  upon  the  target  when  the  tele- 
scope itself  is  rotated.  In  many  cases  it  will  be  seen  that  the 
whole  field  of  view  moves  up  and  down  and  from  side  to  side 
as  the  telescope  is  rotated,  but  this  is  immaterial ;  the  whole 
point  to  be  gained  is  so  to  adjust  the  cross  lines  that  the  inter- 
section itself  remains  steadily  upon  the  same  distant  spot 
through  a  rotation  of  the  telescope  of  360°. 

When  bore  sighting  on  battens  or  at  short  distances  there 
will  be  parallax  in  all  bore  sights.  This  can  be  best  mini- 
mized by  placing  over  the  eye  lens  of  the  telescope  a  paper 
disk  with  a  very  small  hole  in  the  exact  center.  This  centers 
the  eye  at  one  spot  and  eliminates  the  greater  part  of  the 
error  which  would  be  caused  by  the  parallax. 

All  telescopes  when  received  aboard  ship  are  supposed  to 
have  been  accurately  adjusted  and  the  two  sources  of  error 
pointed  out  above  are  eliminated.    Their  adjustments  should, 


GUNNERY  INSTRUCTIONS.  136 

however,  1)0  checked.  It  hus  been  louiid  Uuit,  owing  to  di.s- 
ji.*j.senibling  for  cleaning  purposes  or  other  causes  aboard  ship, 
all  telescopes  returned  to  the  guu  factory  for  overhaul  and 
repair  or  sent  to  the  fleet  repair  ship  for  repairs  have  been 
out  of  adjustment,  due  to  one  or  both  of  the  above-described 
causes.  The  obvious  remedy  is  that  these  telescopes  should 
not  be  disassembled  for  cleaning  purposes  aboard  ship.  If 
necessary  to  have  them  overhauled,  they  should  be  sent  to 
the  repair  ship  for  cleaning  and  adjustment. 

A  new  bore-sight  telescope  now  in  contemplation  is  so  de- 
signed that  tlie  bad  features  of  the  present  bore-sight  tele- 
scope will  be  eliminated.  It  is  expected  that  this  new  bore- 
sight  telescope  will  be  furnished  to  all  ships  now  under  con- 
struction, and  that  it  will,  in  time,  replace  the  bore-sight  tele- 
s(!bpes  now  in  use  abojird  ships  in  commission. 

319.  Inverting  bore-sight  telescope. — With  the  present  de- 
sign of  bore-sight  telescope,  it  is  not  practicable  to  invert  the 
cross  wires  (turn  them  tln-ough  ISO")  in  order  to  check  for 
error,  as  it  necessitates  a  loosening  of  the  parts  of  the  tele- 
scope, thus  destroying  adjustments  already  made.  A  new 
l)ore-sight  telescope  has  been  designed,  but  not  yet  adopted, 
which  provides  for  inverting  the  cross  wires  in  order  to  check 
the  setting.  At  present  it  is  necessary  to  invert  the  muzzle 
disk  as  a  check  on  the  centering  of  the  bore-sight  telescope 
as  described  in  article  317. 

320.  Method  of  bore  sighting. — Three  persons,  generally 
the  division  officer  and  two  junior  officers,  do  the  work,  at  the 
same  time  utilizing  the  pointers  to  verify  the  results.  (It  is 
always  well  to  have  the  pointers  check  the  bore  sighting  of 
their  gun,  for  then  they  can  not  attribute  erratic  shooting  to 
poor  bore  sighting.) 

Frequently  ships  have  a  regular  "  bore-sighting  board " 
composed  of  the  gunnery  officer  and  two  division  officers. 
This  board  makes  a  final  check  of  all  guns  that  have  been  bore 
sighted.    The  value  of  this  scheme  is  readily  seen. 


136  GUNNERY  INSTRUCTIONS. 

Ill  making  the  adjiisluients.  one  officer  is  statioued  at  the 
l)reech  telescope,  one  at  the  elevating  telescope,  and  the  other 
at  the  training  telescope. 

It  must  be  remembered  that  with  yoke  sights,  a  movement 
of  the  pivot  bar  moves  both  telescopes  so  that  it  is  necessary 
to  have  an  independent  means  of  adjusting  one  of  them.  This 
adjustment  is  accomplished  by  two  tangent  screws  with  clamp 
bolts,  placed  under  the  holder  of  the  training  telescope.  The 
pointing  (elevating)  telescope  is  adjusted  by  the  sight  bar  and 
azimuth  head. 

It  is  necessary  to  make  the  first  adjustment  on  the  elevating 
telescope  and  then  the  training  telescopic  adjustment.  Either 
the  horizontal  or  the  vertical  wires  of  telescopes  may  be  ad- 
justed first. 

For  example,  the  officer  at  the  breech  coaches  in  elevation 
and  train  until  his  horizontal  wire  rests  upon,  say,  the  top 

edge  of  the  target  when  he  calls  out  "  Mark !  Mark ! "  so 

long  as  the  horizontal  wire  of  the  breech  telescope  remains  in 
that  position.  The  man  at  the  elevating  telescope  notes  how 
much  his  horizontal  wire  is  off,  and  by  moving  the  sight  bar 
brings  this  wire  "  on  "  to  coincide  with  that  of  the  breech 
telescope.  In  the  meantime  the  observer  at  the  training  tele- 
scope notes  how  much  his  horizontal  wire  is  ofE  and  after  the 
elevating  pointer  has  made  his  adjustment  the  trainer  brings 
his  "  on  "  by  means  of  the  tangent  screw  under  the  telescope 
holder,  so  that  when  it  is  adjusted  all  three  horizontal  wires 
will  be  "  on  "  at  the  same  time. 

The  three  observers  change  places  and  check. 

The  same  procedure  is  carried  out  for  the  adjustment  of  the 
vertical  wires.  The  man  at  the  breech  coaches  the  trainer, 
calling  out  "Mark !  Mark !"  so  long  as  the  vertical  wire  of  the 
bore-sight  telescope  remains  "on."  The  elevating  pointer  notes 
how  much  the  vertical  wire  of  the  elevating  pointer's  tele- 
scope is  "ofE"  when  that  of  the  breech  telescope  is  "on"  and 
by  moving  the  azimuth  head  brings  it  "on."    In  so  doing  he 


GUNNERY  INSTRUCTIONS.  187 

necessarily  moves  the  vertical  wire  of  the  training  telescope 
through  the  same  angle,  so  that  the  man  at  the  training  tele- 
scope will  have  to  wait  to  make  his  adjustment  until  after  the 
elevating  telescope  is  adjusted. 

The  trainer  makes  this  adjustment  by  using  the  tangent 
screw  at  the  side  of  the  training  telescope  holder  and  secures 
the  holder  with  the  clamp  bolt.  All  observers  change  places 
and  check  results. 

In  bore  sighting  broadside  guns  that  are  equipped  with 
Iieavy  periscopic  telescopes  that  are  seldom  removed  from  the 
holders  there  are  no  tangent  screws  on  the  holders  for  sep- 
arate adjustment  of  the  trainer's  sight,  and  in  lieu  thereof 
the  cross  wires  of  the  telescopes  can  be  independently  ad- 
justed by  moving  them  in  their  vertical  plane.  The  cross 
wires  may  also  be  rotated  around  their  intersection  as  a  center 
so  as  to  make  them  absolutely  vertical  and  horizontal.  Each 
wire  may  also  independently  be  moved  at  right  angles  to  the 
line  of  sight  without  moving  the  other. 

In  guns  equipped  with  this  type  of  telescope  the  elevating 
pointer's  wires  are  brought  "on"  as  with  other  types  (al- 
though this  can  be  done  by  moving  the  cross  wires),  but  the 
training  pointer  must  be  brought  "on"  by  moving  the  cross 
wires  of  the  training  telescope. 

321.  Adjustment  of  the  sight  scales. — Without  moving  the 
sight  bar  or  azimuth  head,  the  clamp  screw,  securing  the  range 
strip  to  the  sight  bar,  is  loosened  and  the  range  strip  moved 
up  or  down  until  its  zero  graduation  is  opposite  the  reference 
mark  on  the  sight-bar  bracket.  The  clamp  screw  is  then  set 
up  and  the  range  strip  secured. 

The  dial  of  the  multiplying  range  scale  is  then  removed, 
cleansed  of  all  oil,  and  the  holder  and  back  of  strip  washed 
off  with  lye  water.  This  is  to  prevent  the  dial  from  turning 
in  the  holder  when  tke  gun  is  fired.  As  an  extra  precaution 
against  turning,  a  piece  of  emery  paper  may  be  cut  to  shape 
and  placed  between  the  dial  nnd  the  holder.    Some  sights  ai'e 


138  GUNNERY  INSTRUCTIONS. 

so  constructed  that  instead  of  moving  the  dial  tlie  zero  mark 
on  the  holder  may  be  adjusted. 

The  friction  clutch  on  the  azimuth  drum  is  loosened,  and 
the  drum  rotated  until  the  "50"  mark  is  under  the  pointer  on 
the  azimuth  hend  when  it  is  then  secured.  In  some  sights  the 
pointer  may  be  moved  l)y  tangent  screws  to  its  position  over 
the  zero  mark  on  the  drum. 

The  muzzle  disk  is  now  again  placed  in  the  muzzle  so  as  to 
check  up  and  make  certain  that  the  telescope  in  the  breech 
disk  has  not  been  accidentally  deranged  during  the  bore 
sighting. 

Very  often  the  square  marks  on  the  reference  pointers  for 
both  range  and  deflection  scales  are  very  dim.  This  may  be 
remedied  by  rubbing  a  small  quantity  of  white  paint  over  the 
mark  engi-aved  upon  the  pointers,  and  then  wiping  off  all 
except  that  which  has  settled  into  the  engraving. 

Before  removing  the  bore-sight  telescope,  move  the  sight 
bar  and  azimuth  head  away  from  zero,  then  return  to  the  zero 
readings  again.  Now  observe  whether  or  not  the  cross  wires 
of  all  three  telescopes  intersect  at  the  target.  If  they  do  not 
it  is  an  indication  of  lost  motion  in  the  scales  or  binding  of 
parts.  This  error  should  not  be  greater  than  4  inches  on  a 
target  1,450  yards  distant,  in  sights  that  have  micrometer  at- 
tachments, but  it  should  be  inappreciable  in  direct  reading 
sights. 

322.  After  bore  sighting. — Remove  breech  telescope  and 
breech  disk  and  return  them  to  proper  custodian.  Cover  the 
pointing  telescopes  with  flannel  covers.  (If  circular  pieces 
of  blotting  paper  are  inserted  inside  the  dust  caps  it  will  be 
found  that  they  aid  greatly  in  preventing  moisture  collecting 
upon  the  object  lenses.) 

A  sign,  such  as  "hands  off,"  or  "this  gun  has  been  hore 
sighted"  will  prevent  thoughtless  men  from  tampering  with 
the  sights. 


GUNNERY  INSTRUCTIONS.  189 

The  peep  sights  carried  alongside  the  telescope  in  holders 
slioidd  be  horo  sighted  after  adjusting  the  telescopes.     This 
is  accomplished  in  the  .same  manner  as  for  the  telescopes,  ex- 
cept that  both  the  elevating  and  ti*aining  sights  are  brought 
■on"  by  moving  the  cross  wires  in  their  respective  holders. 

323.  Turret  bore  sig'hting'. — The  bore  sighting  of  turret 
gun><  follows  the  general  plan  previously  described  for  broad- 
side guns.  Before  adjusting,  the  parallelogram  of  parallel- 
motion  sights  should  always  be  carefully  tested.  This  is  done, 
first,  by  raising  and  lowering  the  sight  bar  and  being  assured 
llial  the  sight  mechanism  is  in  proper  working  order,  by 
l)la<ing  the  bore-sight  telescope  in  the  breech  diaphragm,  and 
ihen  centering  the  bore  upon  a  distant  object.  The  sight  of 
I  lie  elevating  pointer  is  then  brought  on  the  .same  object  by 
moving  the  pivot  bar.  The  gun  is  then  elevated  to  extreme 
elevation  and  again  depressed,  the  observer  at  the  breech  tele- 
scope calling  out  "Mark!  Mark! "  when  the  cross  wires 

of  the  breech  telescope  are  again  "  on,"  and  the  observer  at  the 
cli'vating  telescope  again  notes  the  position  of  his  wires.  The 
gun  is  then  run  down  to  extreme  depression  and  elevated  until 
the  cross  wires  of  the  breech  telescope  are  again  on  the  object. 
The  position  of  the  cross  wires  of  the  sight  telescope  is  noted 
again    when    the    observer    at    the    breech     calls     "Mark! 

Mark!   "     Each  time  that  the  observer  at  the  breech  is 

•  on,"  the  observer  at  the  elevating  telescope  should  be  on. 
l^rrors  will  appear  as  follows : 

^\■llen  the  gun  is  depressed  from  extreme  elevation,  the  line 
of  sight  of  the  elevating  telescope  may  be  above  that  of  the 
breech  telescope,  or  when  the  gun  is  elevated  from  extreme  de- 
l)ression  the  line  of  sight  of  the  elevating  telescope  may  be 
below  that  of  the  breech  telescope.  This  may  be  due  to  the 
following : 

Looseness  in  the  bearings  of  the  parallel  motion. 


140  GUNNERY  INSTRUCTIONS. 

Springing  ol:  eitlier  the  pivot  bar,  conuectiug  arm,  or  con- 
uectiug  bar,  caused  by  tight  bearings.  (Be  extremely  careful 
to  keep  all  oil  holes  clear  and  well  supplied  with  oil.) 

Sliifting  of  the  trunnions  due  to  too  great  clearance. 

Knowing  the  distance  to  the  object  sighted  on,  by  measuring 
the  discrepancies  in  the  vertical  plane,  the  angular  amount  of 
these  discrepancies  may  be  ascertained. 

324.  Importance  of  keeping  clear  of  sight. — It  is  very  im- 
portant at  all  times,  especially  when  bore  sighting  or  shooting, 
that  no  one  should  lean  against  or  exert  any  pressure  on  any 
part  of  the  sight  mechanism. 

325.  Checking  sights  after  firing. — As  soon  as  practicable 
after  firing,  the  sights  should  be  examined  and  any  derange- 
ment, such  as  slipping  of  the  range  strips  and  dials,  etc.,  to- 
gether with  causes,  should  be  noted,  and  the  fact,  together 
with  appropriate  remarks,  should  be  entered  in  tlie  battery 
journal. 

326.  Droop  as  affecting  bore  sighting.— (See  arts.  315, 
4.59.)  There  is  a  diversity  of  opinion  as  to  whether  droop 
should  be  taken  into  consideration  when  bore  sighting.  If 
not,  then  our  present  method  of  bore  sighting  is  correct.  If  it 
is  considered  as  having  an  effect,  then  our  method  of  bore 
sigliting  must  be  changed.  Instead  of  placing  a  disk  in  the  muz- 
zle to  bore  sight  it  would  have  to  be  placed  at  or  near  the  cen- 
ter of  gravity,  which  would  be  little  forward  of  the  trunnions. 
This  would  insure  a  straight  line  through  the  gun,  coincident 
with  the  longitudinal  axis,  through  the  rigid  part;  that  is. 
from  breech  to  center  of  gravity,  but  divergent  from  the  c.  g. 
to  the  muzzle  by  an  amount  equal  to  the  droop.  A  new  source 
of  error  would  be  introduced.  In  order  to  have  a  steady  cen- 
ter disk,  a  long  bearing  surface  is  necessary,  and  since  the 
disk  must  be  inserted  from  the  muzzle  end.  a  slight  clearance 
must  be  allowed.  Erosion  and  wearing  away  of  the  rifling  is 
greatest  at  the  origin  and  decreases  toward  the  muzzle.    This 


GUNNERY  INSTRUCTIONS.  141 

would  make  a  greater  clearance  when  the  disk  reaches  its 
position  over  the  c.  g.  than  at  the  muzzle,  throwing  the  peep- 
hole off  the  center,  by  an  amount  which  in  many  cases  may 
exceed  the  amount  of  the  droop.  So  far  as  known  at  present, 
droop  should  not  he  considered  in  bore  sighting. 


CHAPTER  14. 
FIRE-CONTROL  TELEPHONES. 

327.  Comparison  between  fire-control  telephones  and  com- 
mercial or  ship's  service  telephones. — The  design  of  the  tire- 
control  telephone  is  necessarily  special,  due  to  the  fact  that 
it  must  be  designed  to  meet  practically  the  same  conditions 
as  the  commercial  telephone ;  and  also,  it  must  be  capable  of 
worliing  in  multiple  with  a  number  of  other  telephones.  Pre- 
cautious must  therefore  be  talien  to  build  a  telephone  which 
is  capable  of  withstanding  considerably  larger  currents  than 
the  commercial  telephone,  and  which  possesses  such  physical 
characteristics  that  rough  usage  and  even  exposure  to  the 
worst  atmospheric  conditions  will  not  make  the  service  bad 
or  the  telephone  inoperative.  With  these  conditions,  it  is 
manifestly  impossible  to  attempt  to  develop  an  efficient  fire- 
control  telephone  which  will  compare  favorably  in  cost  with 
the  commercial  telephone. 

328.  Types  of  fire-control  telephones. — In  order  to  meet  all 
conditions,  the  department  has  approved  several  types  of  fire- 
control  telephones,  the  type  depending  upon  the  use  to  which 
it  may  be  put. 

The  Bureau  of  Steam  Engineering,  recognizing  the  weak- 
ness of  a  system  in  which  a  number  of  types  are  involved, 
has  devoted  a  great  deal  of  time  to  the  development  of  a  fire- 
control  telephone  which  will  eliminate  the  use  of  or  the  neces- 
sity for  so  many  types.  As  a  result  of  this  work  and  ex- 
haustive experiments,  two  new  types  have  been  decided  upon 
in  lieu  of  the  numerous  types  previously  used.  It  is  the 
department's  intention  to  supply  all  vessels  in  commission 
with  the  new  type  of  telephone  at  an  early  date. 

142 


GUNNERY  INSTRUCTIONS. 


148 


329.  Types  in  use. — The  principal  types  now  in  use  lire  as 
lollows : 

(a)  Tyi)e  C  telephone  consists  of  ilu-  inicroplione  receivers, 
(•(tiiiiected  in  parallel.  This  telephone  is  used  for  sight  setters 
ill  stations  where  receivers  are  uot  required. 

[h)  Ti/pe  CP  telephone  consists  of  the  microplione  receivers, 
as  used  in  the  type  C  te;lephone.  and  a  transmitter  which  is 
ill  parallel  with  tlie  i-eceivers.  This  telephone  is  used  in  a 
few  places  where  one  transmitter  must  connnuiiicate  with  a 
large  number  of  receivers,  such  as  sv;bstation  transmitters  to 
turret  sight  setters  and  chief  fire-control  officer's  transmitter 


RE.CC1VCRS 


RE.CE.IVERS 


8 


PUUC 


Latest  type  C  telephone  receivers 
series  connected. 


(>riginal  type  C  telephone  re- 
ceivers multiple  connected. 


to  all  turret  (iflicers"  teh'phones.     There  are.  therefore,  fewer 
type  CP  telei)hones  supplied  than  any  otlier. 

(c)  Tijpe  CS  telephone  consists  of  the  microphone  receivers 
of  the  type  C  telephone,  with  tJie  addition  of  a  tran.smitter 
which  is  ///.  .series-  with  tlie  receivers.  1'liis  teIei)lione  is  u.sed 
by  siglit  setters,  by  the  fire-control  party,  and  generally  in  all 
receiving  locations  where  the  type  CP  telephone  is  not  em- 
ployed. 


144 


GUNNERY  INSTRUCTIONS. 


RCCEUVCRS 


RtCClVCRS 


rVWu 


i** 


,,  TRANS. 


:i;el 


RUOGi  &  JACK 


TRAHS. 


=t=»^— 


PUUGi  &.  JACK 


PUUGi 


Spuuq 


Type  CP  telephone. 


Type  CS  telephone. 


«e:ce>ve:r5 


tz 


XRAHS. 


i 


1 


U^ 


II I  CON  D. 


TV  PC  G-£  JACK 

W\TH  TRANS  ARCCEIVELR 
PLUGiS   »NSC«TE.D. 


TO    \.\NE. 

Type  CT  telephone. 


GUNNERY  INSTRUCTIONS. 


146 


(d)  Tyixi  CT  has  the  same  characteristics  as  the  type  CS 
telephone,  epccept  that  the  transmitter  and  receiver  plug  sep- 
arately into  a  type  G-2  jack,  which  is  of  special  construction, 
containing  a  2-m.  f.  condenser.  On  account  of  the  cost  of  the 
special  jacks  few  of  these  telephones  are  in  use. 

Since  two  separate  lines  are  necessary  from  the  jack,  the 
type  is  not  considered  entirely  practical. 


5= 

Operators    ^ 
RE.cEivefi-4; 

1  1 

-TT 

T 

^ 

<?> 

^ 

^ 

_J) 

f       ^ 

^ 

Fig  A. 


RE.ceive»t 


Pig.  B. 


330.  Conditions  governing'  use  of  different  types  of  trans- 
mitters.—  (a)  From  figure  A,  note  that  on  a  given  line  all 
receiving  sets,  since  they  are  plugged  across  the  lines,  are  in 
parallel.  Therefore,  the  current  which  goes  through  lines  T 
and  TT  at  the  point  indicated  is  the  sum  of  all  the  current  re- 
quired for  each  set  of  receivers,  or  the  current  of  one  set  times 
the  number  of  sets  in  use. 

The  source  of  direct  current  for  this  line  is  B  and  BB  and 
through  impedance  coils  P  and  PP.  Similarly,  the  source  of 
34776—18 10 


146 


GUNNERY  INSTRUCTIONS. 


alternatiny  or  talking  current  for  all  the  receivers  is  the 
transmitter  M,  which  receives  its  impulses  when  sound  waves 
strike  the  diaphragm  D  and  cause  it  and  the  upper  electrode 
(to  which  it  is  secured)  to  vibrate,  thus  varying  rapidly  the 
lesistauce  in  the  small  carbon  particles  and  sending  forth  the 
impulses  to  the  receivers.  But  if  this  transmitter  were  in 
series  witli  its  receiver  (instead  of  in  parallel),  its  total  out- 


RCCEltVERS 


KaMF 

COMDE.NSE.K 
PUOQ  . 


Type  CC  telephone. 

put  would  be  limited  by  the  resistance  of  the  receiving  set; 
or  the  talking  energy  supplied  for  the  whole  line  would  really 
be  only  what  is  necessary  for  a  small  portion  of  it.  Since  a 
comparatively  large  amount  of  energy  must  be  emitted  from 
the  receiver  iu  this  case,  it  is  obvious  that  the  parallel  connec- 
tion is  the  only  practicable  one. 

ib)  For  the  same  reason,  on  lines  having  a  few  receivers, 
a  series  connection  is  used  (fig.  B).  It  would  be  satisfactory 
to  use  a  parallel  connection  on  these  lines,  except  that  larger 
currents  than  necessary  would  flow  through  the  transmitter, 
and  in  this  case  there  would  be  danger  of  heating.  It  is 
considered  more  satisfactory  always  to  keep  the  current  (di- 
rect) as  small  as  possible.  In  a  CS  telephone,  as  shown  on 
sketch,  it  is  obvious  that  the  aiuount  of  current  flowing 
through  the  transmitter  is  limited  by  the  higher  resistance 
of  the  receiver  coils. 


GUNNERY  INSTRUCTIONS. 


147 


331.  New  types. — All  of  the  above-mentioned  type.s  are  to 
be  abandoned,  and  new  types,  as  follows,  furnished  to  all 
ships : 

(a)  Type  CC:  The  type  CC  telephone  is  modeled  after  the 
present  type  G  telephone,  except  that  the  plug  is  so  designed 
as  to  have  a  J-m.  f.  condenser  Installed  as  a  part  of  it,  and  the 


BELCEIIVCKS 


r-O 


l^ — o — I 


TRAHS 


w 


PUUCJ&JACK 


POSH 

Button 


Ijll  Vz Mr 

CONOE.NStR 


B 


PLUG, 


Type  CN  telephone. 

receivers  are  in  series.  Tliis  will  enable  all  type  C  telephones 
to  be  lifted  at  small  expense  with  condensers,  and  will  neces- 
sitate no  change  in  tlie  present  equipment  other  than  the  use 
of  the  new  plug  in  place  of  the  old,  and  a  slight  modification 
in  wiring  up  the  head  set. 

(6)  Type  CN:  The  type  CN  telephone  consists  of  receivers 
similar  to  receivers  of  the  type  CC  telephone,  in  conjunction 
with  a  new  design  transmitter  having  conical  electrodes,  and 
also  incorporating  as  an  integral  part  of  the  set  a  ^-m.  f.  con- 


148  GUNNERY  INSTRUCTIONS. 

(leiiser.  aud  a  cut-out  push  button,  which  uiust  be  closed  wheu 
talking.  New  mechanical  features  of  design  have  also  been 
incorporated  in  this  telephone. 

332.  Care  and  operation. — {(i)  Test  fire-control  telephones 
daily. 

(  h )  Use  spare  telephones  frequently,  as  a  certain  amount  of 
usage,  in  addition  to  checking  their  condition,  makes  them 
more  efficient.  The  worst  thing  that  can  be  done  for  the  effi- 
ciency of  the  fire-control  system  is  to  lay  the  telephones  up 
where  they  will  not  be  used  for  a  considerable  period  of  time. 

(c)  Never  carry  a  telephone  by  the  cord,  and  grasp  the  top 
of  the  plug  when  unplugging.  Telephones  now  in  use  have 
practically  all  the  strain  taken  on  the  terminals,  and  these 
precautions  must  be  taken  to  avoid  pulling  loose  a  connection, 
and  thus  rendering  the  telephone  inoperative. 

(d)  Avoid  bending  the  cord  sharply  dver  the  edge  of  the 
terminal  tube.  This  gradually  breaks  through  the  braid  and 
insulation,  in  addition  to  straining  the  copper  conductors,  and 
a  short  circuit  or  open  circuit  results. 

■  (c)  When  talking,  keep  transmitter  in  an  approximately 
vertical  position.  If  the  transmitter  is  placed  horizontally, 
transmission  becomes  very  bad.  since  the  upper  electrode 
presses  on  the  carbon  particles ;  and,  consequently,  the  vi- 
brating impulses  are  dampened.  In  case  the  transmitter  is  in- 
advertently held  horizontally,  bring  same  back  nearly  ver- 
tical, aud  tap  sharply  a  couple  of  times  with  the  hand ;  normal 
operation  should  then  be  obtained. 

(/)  Often,  when  transmitters  have  been  used  for  a  consid- 
erable period  of  time,  heating  is  noticed.  This  is  due.  probably, 
to  the  large  number  of  receivers  to  which  the  transmitter  is 
connected,  and  the  best  thing  to  do  is  to  put  in  a  new  trans- 
mitter, and  allow  the  heated  one  to  cool  off  gradually. 

(fl)  Receiver  diaphragms  sometimes  become  hot:  and,  as  a 
result,  the  paraffin  melts,  collects  in  a  drop,  and  the  receiver 
is  practically  deadened.     It  is  a  matter  of  only  a  few  minutes 


GUNNERY  INSTRUCTIONS.  149 

to  reiiiovo  tlie  cause  ot  the  tnnil)U»;  hut,  ordinarily,  it  is  better 
to  use  a  spare  liead  set.  and  allow  the  heated  receivers  to  cool 
off.  The  receiver  diaphrauni  can  be  put  in  condition  again 
with  little  trouble. 

(h)  C'l-oss  tallc  is  caused  most  frecpiently  by  insufficient  im- 
pedance ;  however,  if  everything  is  going  along  normally  and 
cross  talk  is  noticed,  the  voltage  of  the  system  should  be  in- 
vestigated at  once;  llie  chances  are  that  11  is  high.  Fre- 
quently, when  imi)edance  coils  have  been  in  use  for  a  long 
time,  it  will  be  found  necessary  to  reduce  the  working  voltage 
several  volts  in  oi'der  to  les.sen  cross  talk. 

333.  Impedance  coils. — The  impedance  coil  is  an  inductive 
resistance  coil,  whose  fiuiction  is  to  pi'omote  the  supply  of  di- 
rect cni-HMit  to  the  telephone,  and  to  conhue  the  variations  of 
current  caused  by  talking,  which  are  alternating  in  char- 
acter, to  its  own  circuil.  Thus,  in  preventing  the  leakage  of 
these  altei-nating  impulses  to  other  circuits,  the  impedance 
coil  performs  its  function  of  preventing  cross  talk.  All  tele- 
l)hones.  in  any  circuit,  are  in  parallel;  therefore,  the  more 
telephones  there  are  connected,  the  more  current  is  needed  in 
;i  circuit  to  give  each  telei)hone  its  proper  share.  For  this 
i-eason,  3-ohm  coils  are  used  where  a  large  number  of  tele- 
l)hones  are  employed,  and  10-ohm  coils  where  a  small  number 
are  employed. 

Experiment  has  shown  that  10-ohm  impedance  coils  give 
good  talking  results  with  from  2  to  10  telephones,  and  that 
3-ohm  impedance  coils  give  similar  i-esults  with  from  6  to  20 
telephones. 

334.  Condensers. — A  condenser  is  an  electrical  appliance  so 
constituted  that  electromotive  force  applied  to  it  stores  up 
energy  in  the  form  of  electrostatic  stress,  which  latter  starts 
tills  energy  back  in  the  form  of  current  when  the  constraining 
electromotive  force  is  removed. 

In  the  case  of  lire-control  telephones,  where  the  inductance 
(impedance)    and   capacity    (condensers)    are  in   series,   the 


160  GUNNERY  INSTRUCTIONS. 

talking  efficiency  is  improved.  In  sucli  a  case  the  only  current 
which  goes  through  the  telephone  receivers  is  alternating  in 
character,  and  is  generated  when  the  diaphragm  of  the  trans- 
mitter receives  its  impulses  from  talking,  and  hence  is  neces- 
sarily very  small.  Under  normal  conditions  therefore,  no 
heating  or  other  deleterious  effects  due  to  the  flow  of  current 
will  be  obtained  in  receivers  when  these  small  condensers  are 
used. 

One-half  m.  f.  conden.sers  are  used  in  series  with  the  new 
fire-control  receiving  sets  (tyjDes  CC  and  CN). 

335.  Source  of  energy. — On  vessels  up  to  and  including  the 
Arkansas  and  Wyoming,  the  fire-control  telephone  switch 
panel  may  be  energized  by  either  of  two  telephone  motor 
generators.  Later  ships  are  supplied  with  one  motor  gener- 
ator and  a  storage  battery.  The  storage  battery,  like  the 
motor  generator,  is  arranged  to  supply  the  ship's  service  tele- 
phone system  as  well  as  the  fire-control  system.  The  battery 
is  of  sufficient  capacity  to  supply  current  for  telephones  for  a 
period  of  30  days'  continuous  use. 

The  storage  battery,  consisting  of  an  appropriate  number  of 
Edison  cells,  is  so  designed  as  to  "  float  in  "  on  the  line.  The 
battery  should  first  be  charged  from  ship's  circuit  to  its  nor- 
mal potential,  and  then  be  thrown  in  across  the  motor  gener- 
ator lines  with  the  telephone  outlets.  The  motor  generator 
leads  are  fitted  with  a  reverse-current  circuit  breaker.  If,  for 
any  reason,  the  motor  generator  is  suddenly  stopped,  or  should 
the  voltage  of  the  motor  generator  fall  below  the  normal  re- 
quired, the  battery,  being  across  the  line,  will  automatically 
take  charge  and  supply  the  telephones,  while  the  reverse-cur- 
rent circuit  breaker  will  instantly  open  and  thus  prevent  the 
battery  being  short  circuited  through  the  armature  windings 
on  the  motor  generator. 

336.  Specifications  and  telephone  pamphlets. — IMore  de- 
tailed information-of  fire-control  and  ship's-service  telephones 
may  be  obtained  from  specifications  and  plans  which  are  on 


GUNNERY  INSTRUCTIONS. 


151 


filo  ill  tlie  liiii-t'iiu  of  Steam  Kngineeriny;,  (-((iVk's  ol'  whicli  may 
be  obtained  upon  request,  and  from  Bureau  of  Steam  En- 
gineering Pampldet  No.  1773.  The  following  books  are  rec- 
(>mmended : 

American  Telephone  I'ractice.  by  Miller. 

A  P.  C  of  the  Telephon(>.  by  Homans. 


SW  >TCM   OM  IMT. 

COM.SWBD. 


TE.UC.PHOISC    MOTOR-G,CH. 
iriT.  COt-l.ROOM  . 


2\JVI 


<WEq    [CI 


F-C-TCUE.  SWBO. 
SUBCENTRAV, 


rc.TCLEBUS 


TEUCPHONE   STORAQC    BATTERY 
IN    BATTERY    CHAR<;iNQ    STATJOU 


-TO    CHARC^IN*;    Rt&lSTANCEi 


»    STORAac   BAT.  CHARQiMG;    PANCl.. 

Arrangement  of  curreut  supiJly  lor  I-".  ('.  telephoiits. 


CHAPTER  15. 
RANGE  FINDERS. 

337.  General. — Attention  is  called  to  Ordnance  Pamphlet 
No.  357,  which  gives  detailed  de^ci'iptions  of  the  various  range 
finders  in  use.  These  instruments,  like  all  otlier  delicate  appli- 
ances, require  careful  handling.  Expertness  and  familiarity 
with  the  instrument  depend  on  the  amount  of  intelligent  and 
zealous  effort  devoted  to  practice  under  service  conditions  by 
operators.  The  range-finder  crews  are  most  important  mem- 
bers of  the  fire-control  group.  They  should  be  carefully 
selected  and  schooled  in  their  duties. 

338.  Care  of  range  finders. — When  not  in  use,  and  particu- 
larly during  moist  weather  or  hot  sunlight,  the  range  finders 
mounted  in  the  open  should  be  carefully  protected  by  water- 
proof covers.  Never  expose  instrument  to  intease  heat  or  to 
rain  where  possible  to  avoid  it.  Never  put  a  wet  instrument 
into  its  box,  or  damp  cloths  and  accessories  in  the  box  with  it. 
Tlie  shutters  over  exposed  lenses,  and  the  lioods,  in  the  case 
of  instruments  mounted  in  turrets  and  fire-control  towers, 
should  be  kept  closed.  Stands  should  be  rigidly  secured  to 
the  deck.  Working  parts,  such  as  base  of  cradle,  rings,  and 
rollers  in  cradle  should  be  well  lubricated.  Only  clean  cloths 
(linen),  clean  chamois,  or  paper  provided  for  the  purpose 
should  be  used  to  wipe  the  lenses.  Coverings  of  all  openings 
should  at  all  times  be  securely  closed.  Never  expose  the  inte- 
lior  to  open  air  except  in  dry  weather,  when  it  may  be 
opened  if  necessai-y  for  a  short  time  to  dry  out  the  instru- 
ment.    No  one  except  an  expert  should  attempt  to  take  the 

152 


GUNNERY  INSTRUCTIONS.  153 

iiislruiiieiit  ;ii»:u-l:,  ami  lorce  shuuld  always  l)e  avoided  iu  dis- 
mounting or  operating  a  range  tinder.  Be  extremely  careful  iu 
handling  the  instrument,  as  it  is  very  delicate  and  easily 
jarred  out  of  adjustment.  No  one  except  a  member  of  the 
range-finder  party  should  operate,  adjust,  or  handle  the  range 
tinders  used  (or  fii-e-control  puriioses. 

Notes  ox  the  Bausch  tS:  Lomb  B-Metek  Base,  Mark  IV, 

IMODIFICATTON    V,    KaNGE    FtXDER. 

(Although  the  following  applies  particularly  to  the  above 
type,  any  Bausch  &  Lomb  range  finder  may  be  operated  by 
complying  therewith.) 

339.  Operation  of  Bausch  &  Lomb  range  finders. —  (1)  Re- 
move canvas  cover. 

(2)  Wipe  window  glass  with  materials  supplied. 

(3)  Oi)en  middle  window  slide  on  forward  side  of  I'ange 
finder. 

(4)  I'ut  sunshades  on  end  window  glasses  if  ranges  are  to 
be  taken  toward  the  sun. 

(5)  Adjust  instrument  to  height  of  observer  as  follows: 
Turn  knob  on  cylindrical  spindle  case  attached  to  tripod,  one 
or  two  turns  to  the  left,  then  turn  large  wheel  under  azimuth 
circle  to  the  left  luitil  the  eyepiece  is  at  tlie  proper  height. 

(6)  Turn  astigmatizer  knob  to  "out  position"  if  ranges  are 
to  be  taken  during  daylight. 

(7)  Turn  relief  knobs  to  position  marked  "i-elieved  posi- 
tion." If  range  finder  is  fitted  with  relief  levers,  turn  them 
down. 

(8)  Unclamp  range  finder  by  turning  knob  on  the  right  side 
of  the  mount  to  the  left. 

(9)  Focus  eyepiece  so  that  object  is  perfectly  clear  and 
horizontal  dividing  line  appears  sharp. 

(10)  Turn  change  of  magnification  knob  as  desired  between 
stops  to  the  left  for  28  magnifying  power  and  (o  the  right  for 


164  GUNNERY  INSTRUCTIONS. 

].")   ina^iiifyiug  power.      Use  power   which   iiiiikes   the   object 
appear  clearest. 

(11)  To  take  a  rauge,  stand  with  feet  spread  apart,  1  foot 
ill  advance  of  the  otlier,  cliest  firmly  pressed  against  curved 
l)ody  rest.  Place  the  forehead  against  the  rubber  face  piece 
with  the  eye  to  the  eyepiece.  Grasp  the  altitude  lever  in  the 
left  hand,  steadying  it  on  the  end  of  the  curved  body  rest, 
right  hand  grasping  the  measuring  knob.  Swing  the  range 
finder  in  azimuth  and  move  the  altitude  lever  up  or  down  un- 
til the  object  is  seen  in  the  center  of  the  field,  sharply  cut  by 
the  dividing  line. 

(12)  Turn  measuring  knob  slowly  and  bring  upper  half  of 
the  image  to  coincide  with  the  lower  half,  so  that  a  perfect 
image  is  obtained. 

(13)  Read  range  from  the  inside  and  scale  above  the  field, 
the  range  being  indicated  by  a  small  white  indicator  below  the 
scale. 

(14)  Check  reading  by  outside  scale. 

(15)  Observe  the  following  rules: 

(a)  Always  turn  the  measuring  knob  in  the  same  direction, 
so  that  the  upper  half  of  the  image  will  be  brought  into  coin- 
cidence with  the  lower  half  from  the  same  direction. 

(&)  Never  allow  upper  half  of  image  to  pass  by  the  coin- 
cidence and  be  brought  back  to  it  by  turning  the  measuring 
knob  in  the  opposite  direction. 

(16)  After  observing  a  range  always  throw  the  images 
out  of  coincidence  before  taking  the  next  range. 

(17)  Never  turn  measuring  knob  hard  against  the  stop  in 
cither  direction. 

(18)  When  range  finder  is  not  in  use  swing  it  to  original 
position  and  clamp  it.  Turn  relieving  knobs  to  "clamped  posi- 
tion" if  necessary ;  lower  instrument  by  turning  large  wheel 
to  the  right  against  a  stop;  clamp  knob  in  cylindrical  case 
attached  to  tripod ;  close  window  slide ;  remove  sunshades,  if 
used,  and  put  on  canvas  cover. 


GUNNERY  INSTRUCTIONS,  166 

(19)  To  take  ranges  of  lights  at  night,  turn  the  astigmatizer 
knob  to  the  left  to  tlie  "in"  position. 

(20)  Use  amber  eyepiece  if  glare  of  sun  is  very  bright  or  if 
range  is  being  taken  on  a  searchlight. 

340.  Org'anization  of  range-finder  party. — The  organiza- 
tion (if  a  rauiic-lhidri-  party  should  consist  of  the  range-finder 
ollicer  and  such  other  officers  (petty  officers)  and  men  as  may 
be  required  for  the  operation  of  the  instrument  and  the  trans- 
mission of  the  ranges.  Only  men  who  have  good  eyesight 
sliould  be  eligible  for  duty.  Men  detailed  for  duty  as  range- 
finder  operators  should  not  be  changed  and  should  have  the 
same  permanence  in  their  station  as  gun  pointers. 

341.  Operation  of  range  finders. — P^irst  develop  accuracy  in 
fonsecutive  readings  of  fixed  distances  by  taking  a  number 
of  observations,  recording  each  one  carefully  and  honestly. 
An  average  of  these  gives  mean  and  nearly  the  correct  dis- 
tance. The  mean  compared  with  each  reading  gives  the  varia- 
tion from  the  mean  distance,  and  the  average  of  the  variations 
gives  the  mean  variation  which  is  the  measure  of  the  opera- 
tor's accuracy.  The  records  of  an  operator  should  improve 
steadily.  To  guard  against  carelessness  and  to  insure  un- 
prejudiced readings  when  training  an  operator,  it  is  well  to 
cover  the  scale  from  the  view  of  the  operator  and  have  an- 
other operator  read  the  results  of  each  contact.  Always  move 
the  scale  the  same  way  in  making  each  contact.  Always  move 
the  scale  away  from  the  contact  after  each  reading.  Work 
of  this  nature  must  be  carried  on  both  by  day  and  by  night ; 
the  astigmatizer  must  be  used  at  the  latter  times.  Always 
drill  in  conjunction  with  fire  control  when  it  is  possible  to 
do  so.  Several  short  drill  periods  per  day  are  better  than 
one  long  one.  For  a  new  operator  two  half-hour  periods  in 
the  forenoon,  two  in  the  afternoon,  and  one  in  the  evening  are 
necessary.  The  expert  operator  should  drill  daily.  After  ac- 
curacy is  obtained  develop  rapidity  of  operation. 


156  GUNNERY  INSTRUCTIONS. 

342.  The  following  drill  routine  is  recommended. —  (a) 
Test  for  "  duplication '"  or  "  deficiency  "  of  the  image  and  cor- 
rect, if  necessary,  by  the  height  adjuster. 

(6)  Adjust  by  self-contained  adjusting  device. 

(c)  Pick  out  several  well-defined  objects  from  2,000  to 
35,000  yards  distance. 

(d)  Each  member  of  party  take  a  series  of  10  ranges  on 
each  of  tlie  objects,  throwing  the  image  out  of  coincidence 
before  each  range  is  taken. 

(c)  Compare  average  of  10  ranges  with  the  true  distance 
(.btained  from  chart,  and  compare  mean  variations. 

(/)  Record  data  for  each  drill  in  a  range-finder  record 
book.     (Note  slIouLd  be  made  of  the  state  of  the  atmosphere.) 

(g)  Keep  and  compare  each  man's  record  from  day  to  day. 

(h)  Keep  window  slide  closed  over  window  giving  light  to 
inside  scale  and  have  second  observer  record  the  ranges  from 
the  outside  scale.  Be  sure  that  the  outside  scale  is  set  to  cor- 
lespond  with  the  inside  scale. 

(i)  Take  ranges  simultaneously  on  the  same  object  from 
two  or  more  I'ange  finders  and  compare  results. 

ij)  After  the  observer  becomes  expert  take  ranges  on  mov- 
ing objects,  when  the  ship  is  rolling  and  there  is  considerable 
vibration  and  wind.  Take  advantage  when  at  sea  of  oppor- 
tunities to  get  readings  on  passing  vessels. 

(k)  The  average  man  should  become  expert  in  accurately 
taking  ranges  after  being  drilled  daily  for  about  a  month. 


CHAPTER  16. 
SPOTTING. 

343.  Necessity  for  spotting. — For  the  purpose  of  regiilntiiij? 
the  sight-bar  ranges,  range  finders  can  not  now  he  used  ex- 
clusively for  the  following  reasons : 

(cr)  Errors  occur  due  to  faulty  operation  and  adjustment 
and  to  varied  conditions  of  atmosphere. 

(b)  A  range  finder  can  not  be  accurately  calibrated  with 
the  sights  so  as  to  give  directly  the  true  sight-bar  reading  at 
various  ranges. 

(c)  Owing  to  the  errors  of  guns,  the  dispersion  of  shots 
necessitates  observation  of  the  impacts.  As  gunnery  pro- 
gresses it  is  probable  that  precision  will  improve,  and  so  fa- 
cilitate the  control  of  gimfire. 

344.  Range  finder  and  spotting  both  employed. — It  is  rec- 
ognized tliat  the  range-finder  method  would  l)e  ideal  for  regu- 
lating the  sight-bar  ranges;  it  is  also  admitted  that  the  method 
of  spotting  as  employed  at  target  practice  is  crude  and  arti- 
ficial, but  a  compromise  is  necessary,  and  successful  control 
at  present  depends  upon  the  accurate  use  of  both  range  finder 
and  spotting. 

345.  Importance  of  spotter. — Of  the  fire-control  party  the 
spotter  at  present  holds  a  most  important  position.  Upon  him. 
to  a  considerable  degree,  rests  the  responsibility  of  getting 
and  retaining  the  initial  advantage.  As  long  as  one  spotter 
and  one  range  finder  remain,  together  with  a  means  of  com- 
mimication,  an  efficient  collective  gunfire  may  be  maintained. 
When  communications  are  destroyed  the  effectiveness  of  the 
fire  will  depend  on  the  ability  of  the  division  officers  to  con- 
trol and  spot  the  units  under  their  charge. 

157 


168  GUNNERY  INSTHUCTIONS. 

346.  Power  of  glasses. — Considering  the  various  ranges  and 
conditions  of  weather  that  may  obtain  in  battle,  the  most 
suitable  power  for  a  day  spotting  glass  is  10.  On  hazy  days 
a  somewhat  lower  power  would  give  slightly  better  results, 
but  not  sufficiently  better  to  warrant  a  change  in  the  power  of 
the  glass.  On  bright  days  a  higher  power.  1.5  or  more,  may 
be  used  to  advantage.  Were  it  not  for  the  reduction  in  size 
of  the  field  and  the  loss  of  light  which  accompany  an  increase 
in  power  it  would  not  be  possible  to  establish  an  upper  limit 
of  magnification. 

The  Mark  I  spotting  glass  (which  is  similar  to  a  li  meter 
range  finder  in  appearance)  has  both  10  and  1.5  powers. 

The  Mark  III  spotting  telescope  has  a  power  from  20  to  30, 
in  order  that  the  rifleman  using  it  on  a  rifle  range  may  have  a 
high-power  glass  to  gauge  the  refraction. 

347.  Field. — The  field  of  a  day  spotting  gla.ss  should  be  at 

least  2°.     The  10-power  glass  has  a  4°  field,  which  is  none 

too  great  when   opening  fire.     With   a  small  dispersed   and 

well-controlled  fire  a  field  of  2i°    (that  of  a  15-power  glass) 

might  be  sufficient.     The  field  of  a  glass  of  1  power  is  40°. 

that  of  any  other  power  can  be  calculated  by  dividing  this  40° 

by  the  power ;  that  is,  a  10-power  glass  has  a  field  of  4°   (40 

divided  by  10). 

40° 

(a) =field  of  glass. 

^  ^  power  " 

348.  Exit  pupil. — To  give  good  light  and  illumination,  the 
exit  pupil  of  the  glass  should  be  at  least  as  large  as  the  pupil 
of  the  eye.  The  pupil  dilates  in  the  dark :  therefore  a  larger 
exit  pupil  is  needed  at  night  than  during  daylight.  The 
diameter  of  the  exit  pupil  can  be  obtained  by  dividing  the 
diameter  of  the  objective  by  the  magnifying  power. 

The  standai-d  ordnance  night  binocuhir  CMark  1\)  has  an 
objective  30  millimeters  in  diameter ;  a  power  of  5.  and  there- 
fore an  exit  pupil  of  6  millimeters  (0.24  inch).  Both  the 
Bausch  &  Lomb  and  the  Terlux  10-power  day  binoculars  have 


GUNNERY  INSTRUCTIONS.  169 

objectives    45    millimeters    in    diameter,    and    therefore    exit 
pupils  of  4.5  millimeters  (0.18  inch). 

The  exit  pupil  in  a  day  glass  should  be  at  least  0.2  inch  in 
diameter,  while  that  in  a  night  glass  should  be  at  least  0.25 
inch.  A  large  exit  pupil  would  be  advantageous,  in  that  the 
pupil  of  the  eye  would  not  have  to  be  maintained  exactly  in 
line  with  the  exit  pupil  of  the  glass  but  for  the  fact  that  as 
the  exit  pupil  increases  the  power  decreases  (using  same 
diameter  objective). 

...  diam.  objective         .,         ., 

(b) = =exit  pupil 

^  ^  power  ^   ^ 

349.  Laws  governing  optical  characteristics. — There  is 
constant  demand  for  glasses  having  high  power,  large  field, 
and  good  illumination.  The  definite  rules  referred  to  above 
cover  the  characteristics  of  spotting  glasses.  High-powered 
glasses  with  large  fields  can  not  be  constructed  except  as 
already  outlined.  While  increasing  the  diameter  of  the  objec- 
tive does  increase  the  illumination  and  exit  pupil,  it  does  not 
affect  the  field  of  the  instrument.  Increasing  the  length  of 
the  instrument  does  have  a  bearing,  however,  on  the  power. 
The  power  may  be  obtained  by  dividing  the  "  focal  length  of 
the  object  glass  "  by  the  "  focal  length  of  the  eyepiece." 

40 

(a) =  field  of  glass 

^  '  power  * 

,.,  diameter  of  objective         .^         .,     i 

(0) =exit  pupil 

^  '  power  ^  ^ 

,  ,  focal  length  of  objective  _ 

^  '  focal  length  of  eyepiece"*^ 

350.  Binocular  vision. — Binocular  vision  is  desirable  for 
spotting.  Objects  which  when  seen  with  one  eye  appear  flat 
(that  is,  at  the  same  range)  stand  out  when  viewed  with  both 
eyes.  For  spotting  purposes  binoculars  are  therefore  superior 
to  telescopes.  The  IMark  V  periscope  (Ordnance  pamphlet 
No.  416,  April.  1913)  has  binocular  eyepieces,  and  is  intended 
for  spotting  from  fire-control  towers. 


160  GUNNERY  INSTRUCTIONS. 

351,  Stereoscopic  effect. — The  Mark  I  spotting  glass  lias 
been  supplied  in  order  to  increase  the  stereoscopic  effect  ob- 
tained to  a  slighter  degree  with  binoculars. 

3.52.  Mounting. — It  is  of  extreme  importance  that  all  spot- 
ting glasses  be  rigidly  mounted.  While  it  is  difficult  to  keep  a 
long,  high-power  telescope  on  a  target,  a  properly  mounted 
]\iark  I  spotting  glass  can  be  readily  held  there,  and  the  spot- 
ter can  be  protected  by  a  housing,  as  the  objectives  are  1^ 
meters  apart. 

353.  Care  of  eyes. — Considerable  concentration  is  necessary 
in  spotting,  and  the  eyes  are  likely  to  be  strained  unless  fre- 
quently rested.  The  spotter  must  avail  himself  of  opportuni- 
ties for  resting  his  eyes,  so  that  when  needed  they  will  be  in 
normal  condition. 

354.  Methods — "  Direct  flight  "  method. — Where  ranges 
permit  spotting  can  be  best  done  by  "direct  flight."  A  spotter 
takes  a  position- clear  of  smoke  and  gas  and,  through  glasses, 
observes  the  projectile  in  flight.  He  keeps  the  top  of  the 
target  in  the  field  of  his  glasses  and  observes  and  follows  the 
projectile  when  it  enters  the  field  and  at  what  point  it  passes 
the  vertical  plane  of  the  target.  Knowing  then  how  much  of 
a  change  in  range  and  deflection  are  necessary,  he  gives  the 
correction. 

355.  Following  projectiles  in  flight. — On  a  clear  day  pro- 
jectiles can  be  followed  in  flight  by  an  experienced  spotter, 
using  glasses  to  about  the  following  ranges : 

Yards. 

J4,  13,  12,  and  10  inch  guns 5,000 

8,  7,  and  6  inch  guns___ 4,000 

5  and  3  inch  guns 3,  000 

3  and  6  pounder  guns 2,  000 

1-pounder  guns 700 

At  ranges  from  5,000  to  12,000  yards  a  12  or  14  inch  pro- 
jectile may  generally  be  seen  up  to  the  highest  point  in  its 
trajectory. 


GUNNERY  INSTRUCTIONS. 


161 


356.  Calculations  and  diagrams. — Calculations  and  dia- 
grams must  be  made  by  the  spotter  in  order  to  properly  train 
himself  for  his  work. 

357.  Diagram — Day  elementary  practice. — 12-inch  (2,900 
f.  s.  gun),  mean  range,  2,000  yards.  Target  10  by  21  feet 
abeam,  approximately  3  feet  above  deck  of  raft.  Raft  2  feet 
high.  From  column  19,  Range  Tables,  100  yards  on  sight  bar 
changes  point  of  impact  4  feet.  Hence  target  is  250  yards  high 
ou  range  scale.  From  column  18,  14  yards  or  42  feet  equals  12 
knots  on  deflection  drum.  One  knot  then  equals  3.5  feet  on  the 
target.  Hence  the  width  of  this  target  (when  abeam)  is  6 
knots.  ^lake  a  diagram  of  the  target  to  a  convenient  scale 
showing  all  dimensions  with  spotting  corrections  in  yards  and 
knots.    Such  a  diagram  is  shown  in  figure  1. 

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Fig,  I.— Spotting  dfagram— direct  flight  method.     12"  2,900  f.  s.  gun 

range  2,000  yards. 

Note. — The  width  of  screen  shown  in  sketch  is  10   feet.     Scale, 
1"=5  feet. 

3477e— IS 11 


162  GUNNERY  INSTRUCTIONS. 

358.  Diagram  for  night  practice. — Preparatory  to  long- 
range  target  practice  at  night  each  group  spotter  should  make 
spotting  diagram  for  what  is  considered  will  be  the  mean 
range.  Special  study  of  the  range  tables  is  recommended 
(columns  IS  and  19).  For  example,  at  1,000  yards,  6-inch 
guns  (2,600  f.  s.),  change  of  height  of  impact  for  100  yards 
sight  bar  equals  2  feet.  At  5.000  yards  1  knot  detlection 
equals  12  feet,  and  100  yards  in  range  equals  18  feet  change 
of  height  of  impact. 

359.  "  Vertical  "  or  "  splash  "  method.— This  method  is 
mployed  at  short  ranges,  when  projectiles  have  not  been 
een  in  direct  flight,  and  at  all  ranges  greater  than  4,000  yards. 

fhe  spotter  from  an  elevated  position,  the  higher  the  better, 
observes  the  slick  formed  when  the  splash  subsides  or  the 
base  line  of  the  splash.  This  slick  is  pictured  in  the  same 
vertical  plane  as  the  target,  and  an  estimate  is  made  of  how 
much  above  or  below  the  water  line  it  appears.  Knowing 
for  various  ranges  how  much  "  short "  or  "  over "  splashes 
must  be  to  appear  at  certain  vertical  distances  from  the  water 
line,  a  correction  can  be  applied  to  the  sight  bar.  (The  change 
of  range  in  the  interval  of  time  between  shots  must  be  com- 
bined with  spotting  correction,  as  discussed  later  (Art.  410), 
to  give  the  actual  sight-bar  setting.) 

Diagram,  splash  method. — Figure  II  illustrates  the  prin- 
ciple of  the  vertical  or  splash  method. 

FE=Height  of  spotter  above  water  line  of  firing  ship. 
h=FW=Effective  height  of  spotter,  considering  curvature  of 
earth. 
WE=Height  of  eye  for  visible  horizon  corresponding  to 
range. 
B=Splash  of  projectile  falling  distance  b  beyond  target 

T. 
A=Splash  of  projectile  falling  distance  a  short  of  target 
T. 


GUNNERY  INSTRUCTIONS.  163 

FAL— Sputters  line  ol'  sight  to  slick  uf  A. 

FRB=Spotters  line  of  sight  to  slick  of  B. 

y=Apparent  distance  of  A  below  water  line  of  target. 
x=ApparC'nt  distance  of  B  above  water  line  uf  target. 

Figure  III  shows  front  elevation  as  would  be  seen  through 
glasses  with  horizon  sketched  in  corresponding  to  h=120  feet. 
Range,  10,000  yards,  target  30  feet  high. 

360.  Calculations. — Referring  to  Figure  II  it  is  readily  seen 
that  values  of  y  and  x  for  "shorts"  and  "overs"  may  be  cal- 
culated by  the  following  formulas  : 

_hXa  __hxb 

To  calculate  value  of  h  use  Table  6,  Bowditcli.  "  Distance 
of  visibility  of  objects  at  sea."  With  range  in  nautical  miles, 
tind  height  at  which  the  horizon  is  visible.  The  difference 
between  the  height  of  the  spotter  above  the  water  line  and 
the  height  just  fnund  gives  tlie  effective  spotting  height. 


164 


GUNNERY  INSTRUCTIONS. 


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GUNNERY  INSTRUCTIONS. 


166 


166  GUNNERY  INSTRUCTIONS. 

Tables  have  been  calculated  for  "  shorts,"  "  overs,"  and 
"  length  of  target  in  knots  "  for  a  range  of  12,000  yards.  For 
other  ranges  the  calculations  are  made  in  a  similar  manner. 

[Height  of  spotter's  eye,  120  feet  from  water  line;  range, 
12,000  yards;  2,000  yards=l  knot;  a=l,000  yards;  target, 
30  feet  high;  effective  spotting  height=120— 27=93  feet.] 

"  Shorts." 

hXa     93X1000 
y~R^~    11000    ~^'^  ^®*  below  water  line  or  about  one-third 

height  of  target. 


"  Overs." 

hXb     93X1000     „  ,  ^        ,    ,  ,.  ,.  ,    , 

X  ~p~irj>~    iQonn    =7.1  reet  below  water  line  or  slightly  greater 
n-to       16WV  ^j^^j^  one-fourth  height  of  target. 

Length  in  knots  of  60-foot  target  on  12-inch  (2,900  f.  s.) 
deflection  drum— 12,000  yards,  bearing  abeam. 

105X3 

1  knot  =—Y^  =26.3  feet  and  a  target  60  feet  long  abeam  is  2.3 

^^  knots. 

Long  on  12-inch  deflection  drum.  When  bearing  30"  it 
would  be  2.3  X  sine  30° — 1.1  knots.  Hence,  a  splash  appearing 
a  target  length  to  the  left  of  target  would  require  a  spot  of 

2  knots  right ;  whereas  when  the  target  is  abeam  the  spot 
would  be  3.5  knots  right. 

361.  Table  of  shorts  and  overs.-— Target,  30  feet  high  ;  spot- 
ter's eye,  120  feet  above  water  line ;  range  in  yards.  Column 
A— Distance  of  "  slick"  below  ia  feet.  Relative  proportion  of 
target  given  approximately  in  Column  B ;  a=yards  short  of 
water  line  of  target.    12-inch  gun.    2.900  f.  s. 


GUNNERY  INSTRUCTIONS. 


167 


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168  GUNNERY  INSTRUCTIONS. 

Analysis  of  tables.— On  inspectiog  the  tables  it  will  be  seen 
that  the  values  in  column  A  vary  directly  as  the  distance  of 
the  splash  is  "  short "  or  "  over,"  so  that  at  any  range,  if  the 
.spotter  remembers  the  value  of  "  y  "  for  100  yards,  he  can 
tell  what  it  is  approximately  for  500  yards.  At  ranges  short 
of  10.000  yards  the  effect  of  the  curvature  of  the  earth  is  small, 
but  should  be  considered.  At  15,000  yards,  neglecting  the 
earth's  curvature,  a  short  of  1,000  yards,  theoretically,  would 
appear  8.5  below,  whereas  it  will  really  appear  5.5  below.  If 
a  spotter  estimates  the  slick  to  be  5.5  under,  and  considered 
his  height  as  120  feet,  he  would  give  a  spot  of  "  Up  600  "  and 
then  be  400  yards  in  error.  This  may  sometimes  account  for 
'•  under  spotting  "  at  high  ranges. 

362.  Initial  deflection. — To  obtain  tlie  initial  deflection,  at- 
tention is  invited  to  the  problems  given  in  chapter  17. 

The  initial-detlectiou  indicator,  described  below,  is  a  ready 
means  of  obtaining  the  deflection  due  to  speed  of  ship  and 
target,  not  including  the  effect  of  wind. 

The  construction  of  the  initial-deflection  indicator  is  as  fol- 
lows : 

1.  Construct  on  cardboard  a  compass  rose,  indicating  de- 
grees, and  marking  each  5°  position.  The  inner  diameter  of 
this  compass  rose  to  be  about  8  inches. 

2.  Construct  the  speed  and  bearing  diagi-am  as  follows: 
Cut  a  piece  of  cardboard  to  circular  shape,  the  diameter 

being  equal  to  the  inner  diameter  of  the  compass  rose  previ- 
ously constructed.  Draw  on  this  circular  cardboard  two  di- 
ameters 90°  apart.  Mark  one  of  these  with  an  arrowhead 
for  indicating  the  bearing.  On  the  other  diameter  construct 
two  sets  of  circles  tangent  to  the  bearing  indicating  diameter. 
The  scale  of  these  pircles  should  be  such  tliat  a  circle  of 
diameter  of  at  least  twenty  times  the  unit  may  be  constructed 
on  each  side  of  the  center.  The  diameters  should  vary  by  two 
units. 


GUNNERY  INSTRUCTIONS. 


169 


3.  Construct  enemy  arm  from  a  strip  of  celluloid  having  a 
hole  at  one  end  for  pivot,  the  remainder  of  the  arm  to  be  so 
cut  that  if  extended  the  line  would  pass  through  the  center 
of  the  pivot,  as  in  the  sketch.  On  this  arm  lay  off  and  mark 
intervals  from  the  center  of  the  pivot  on  the  same  scale  as 
that  used  for  the  speed  circles. 


B     MOVABUC     ARM    Cr    CE.LLULOID    PlVOTtD   AT     "A" 
C      MOVABLE      ARM     or    CE.LLULOID     PIVOTE.0    AT    "a" 


170  GUNNERY  INSTRUCTIONS. 

4.  Construct  own  ship  arm  similarly  to  enemy  arm  but  lay 
off  intervals  from  center  of  pivot  on  a  scale  one  and  one-half 
times  as  great  as  that  used  for  enemy  arm. 

5.  Secure  all  parts  by  pivot  permitting  motion  of  all  parts 
except  compass  rose. 

To  obtain  the  deflection,  place  the  arrowhead  on  the  inner 
card  pointing  to  the  true  bearing  of  the  target ;  "  Ovni  ship 
arm  "  at  the  ti*ue  course  of  the  ship ;  "  Enemy  arm  "  at  the 
true  course  of  the  enemy  (target). 

Th&  intersection  of  the  speed  circle  with  "  own  ship  arm  " 
indicates  the  knots  correction  for  movement  of  ship. 

Tlie  intersection  of  the  speed  circle  with  "  enemy  arm  "  indi- 
cates the  knots  correction  for  enemy  movement. 

These  corrections  are  right  or  left  depending  upon  whether 
the  direction  of  motion  is  to  the  right  or  left  of  the  bearing  as 
shown  in  red  and  black  ink. 

The  total  correction  to  be  applied  is  the  algebraic  sum  of  the 
two  corrections. 

363.  Deflection  due  to  wind. — A  convenient  though  not  ab- 
solute rule  for  making  allowance  for  the  deflection  caused  by 
wind  is  to  allow  one-half  of  the  force  of  the  wind  shown  on 
the  Beaufort  scale.  If,  for  instance,  the  wind  is  blowing  with 
a  force  of  4  (Beaufort  scale),  2  knots  would  be  about  the 
correct  compensation.  Data  on  the  effect  of  a  wind  can  also  be 
obtained  from  the  range  tables,  but  this  is  believed  to  be  no 
more  accurate  than  would  be  obtained  by  the  use  of  the  fore- 
going rule. 

364.  Thumb  rule. — A  thumb  rule  for  obtaining  the  initial 
deflection  is  as  follows : 

(a)  Correction  ship's  speed  equals  product  of  speed  of  ship 
in  knots,  times  three-fourths  time  natural  sine  of  angle  be- 
tween course  and  bearing  of  target.  This  correction  in  knots 
applied  to  right,  firing  to  starboard ;  firing  to  port. 


GUNNERY  INSTRUCTIONS. 


171 


(b)  Correction  target  speed  equals  plotted  speed  of  target 
in  knots,  times  natural  sine  of  angle  between  course  and  bear- 
ing of  target. 

(c)  Correction  for  wind  equals  one-li:ilf  force  in  knots  by 
Beaufort  scale,  times  sine  of  angle  between  direction  of  the 
wind  and  bearing  of  target.     (This  is  for  the  true  wind.) 

A  spotter  in  the  top  with  a  table  of  natural  sines  at  hand 
for  every  10°  can  quickly  compute  the  initial  deflection  by 
using  these  thumb  rules.  If  he  has  plenty  of  time,  five  min- 
utes for  example,  with  his  range  table  he  can  accurately 
calculate  the  correct  deflection  for  each  caliber  of  guns  fired. 

365.  Tables  of  deflections  (length  of  target  on  deflection 
'drum  in  knots),  assuming  firing  and  target  ships  on  parallel 
courses. 

12-inch,  2,900  f.  s.  gun,  full  charge,  target  60  feet  long. 


Value  of 
1  Imot 
(feet.) 

•     Length  of  target  in 

knots  bearing— 

Range. 

90° 

75°          60° 

45° 

30° 

15° 

Yards. 
6,000 

11.8 
16.3 
21.0 
26.3 
31,8 
37.8 
44.3 
51.0 

5.1 

3.7 
2.9 
2.3 
1.9 
1.6 
1.4 
1.2 

4.8"        4.4 
3.5          3.1 

2.7  2.4 
2. 2          2. 0 

1.8  i        1.6 

3.6 
2.6 
2.0 
1.6 
1.3 
1.1 
1.0 
.8 

2.6 

1.9 

1.4 

1.1 

.9 

.8 

.7 

.6 

1.3 

8,000  

.90 

10,000 

.7 

12,000 

.6 

14,000 

.  0 

16,000 

1.5 

1.4 

.4 

18,000 

1.3 
1.1 

1.1 
1.0 

•4 

20,000 

.3 

Analysis  of  table. — An  inspection  of  this  table  shows  that 
the  greater  the  range  the  smaller  the  length  of  the  target  in 
deflection;  thus  a  12-inch  splash  GO  feet  to  the  left  of  the 
target  abeam  6.000  yards  distant  would  be  spotted  "  Right  8," 
while  at  15,000  yards,  "  Right  3."  It  is  important  to  remember 
this  change.  Attention  is  called  to  the  effect  of  bearing  of 
target  upon  deflection.     (See  art.  360.) 


172  GUNNERY  INSTRUCTIONS. 

366.  Parallax. — When  tiring  at  short  ranges,  where  the 
bearing  of  target  changes  rapidly,  allowance  must  be  made 
for  position  of  spotter  whether  forward  or  abaft  firing  gun. 
For  example,  12-inch  gnu  fires  off  starboard  beam  at  a  target 
l!,000  yards  distant;  speed  of  target,  5  knots;  gun,  10  knots. 
During  the  time  of  flight  the  ship  advances  21  feet.  Hence, 
if  a  spotter  stood  abaft  the  gun  21  feet,  he  would  be  in  the 
original  line  of  fire  when  the  shell  splashes,  and  could  most 
accurately  spot  on  in  deflection. 

367.  Diagram  of  lateral  displacements. — In  Figure  IV  is 
shown  the  lateral  displacement  of  splash  and  triangles  by 
which  lateral  coordinates  of  points  in  "  splash  diagram "  of 
short  range  are  calculated.  Where  range  is  over  8,000  yardfe 
an  inspection  of  Figure  IV  shows  that  the  value  of  X  is  so 

small  as  to  be  negligible,  i.  e.,  ratio  of  -j-^  small  forsplashes  within 

100  yards  of  target. 

At  8,000  yards  a  .splash  1,000  short  is  displaced  only  about 
2  feet  for  difference  of  speeds  of  target  and  firing  ship  of  10 
knots  when  abeam. 


B 

E. 


-~-ir^ 


llo 


Fig.    IV.—Lateral  displacement  of   splash 

368.  Explanation  of  figure. — A  ship  moving  10  knots  fires 
a  6-incli,  2,li00  f.  s.  gun  when  at  A.  The  target  T,  15  by  21 
feet,  is  2,000  yards  off  the  starboard  beam,  and  moving  on  a 
parnllpl  course  ">  knots.     The  diagram  shows  gun  making  5 


GUNNERY  INSTRUCTIONS.  178 

knots  and  target  anchored,  which  gives  the  same  results.  The 
.-•potter  at  A,  3.5  feet  over  gun,  moves  from  A  to  B  during  time 
of  fliglit  of  projectile  from  A  to  point  of  fall,  S.  His  line  of 
siglit  to  splash  BCS,  passes  a  lateral  distance  ./■  to  the  left 
of  T. 

Assume  this  projectile  iiit  in  corner  of  Al,  21  fee,t  above  the 
water :  target  6  feet  above  water.  From  column  19,  range 
rabies,  using  mean  value  of  0  feet=100  yards.  TS=3.50  yai'ds, 
approximately.  Then  from  colunni  18  witli  horizontal  range^^ 
2.350  yards  (not  distance  of  vun  1o  the  target)   distance  AB 

20  5x3X5 
(movement  of  spotter)  is  found  to  be  — ~~Tn =25.6  feet.     By 

similar  triangles,  CT  or  a?=3.8  feet.  From  a  height  of  35 
feet  the  slick  appears  5.2  above  water  line  of  raft.  S'  repre- 
sents splash  short  of  target,  and  seen  a  distance  y  to  right  by 
spotter  who  has  moved  to  E.  Similar  calculations  are  made 
for  hits  in  corners  of  A4,  Yl,  and  Y4.  Having  the  vertical 
and  lateral  coordinate^  of  these  points  a  target  may  be  pro- 
jected on  the  water. 

The  coordinates   ot   the   points   necessary   to   project   the 
".splash   diagram"   are  as  follows    (see   columns  18  and  19, 
range  tables)  : 
Corner  Al : 

x=3.8  feet  to  left  of  Al. 
y— 5.2  feet  above  water  line  raft. 
Corner  A4: 

x=3.8  feet  to  left  A4. 
y=5.2  feet  above  water  line. 
Corner  Yl : 

x=l.l  feet  to  left  of  Yl. 
y=1.7  feet  above  water  line. 
Corner  Y4: 

x=l.l  feet  to  left  Y4. 
y=1.7  feet  above  water  line. 


174  GUNNERY  INSTRUCTIONS. 

369.  Splash  diagram  for  long  rang'e. — Having  calculated 
tables  for  use  in  long-range  spotting  by  the  "vertical"  or 
"splash"  method  construct  a  diagram  to  scale.  The  slick 
lor  range  only  is  shown.  (See  art.  367.)  These  dia- 
grams should  be  constructed  similar  to  Figure  VI  for 
(1000,  8,000,  10.000,  12,000,  15,000,  and  18,000  yards  for 
lioth  high  and  low  spotting  positions.  A  study  of  them  en- 
.-ibles  a  spotter  to  spot  without  reference  to  tables.  The  dia- 
gram constructed  is  for  a  range  of  10,000  yards,  target  30  by 
(50  feet.  Raft  130  feet  long,  4-foot  freeboard  forward  and  aft. 
Scale,  1  inch  equals  15  feet.  Spotting  correction  to  water  line. 
Horizon  appears  15  feet  above  water  line  from  tlie  spotting 
position. 

370.  Training  for  battle. — As  a  preparation  and  training 
for  battle,  the  spotter  should  study  the  types  of  ships  of  his  ad- 
versai-y,  considering  all  the  dimensions  obtainable.  Such  data 
as  lengths,  distance  of  foremast  to  stem,  height  of  smoke  pipe, 
height  of  tops,  turrets,  searchlights,  and  main  deck,  are  valu- 
able. With  these  the  spotter  can  construct  battle  diagrams 
to  scale  and  use  these  known  points  and  dimensions  in  spot- 
ting. In  the  first  firing  on  the  San  Marcos  a  high  explosive 
projectile  was  seen  to  detonate  at  the  top  of  the  smoke  pipe, 
the  kno^^'n  height  of  the  impact  was  used  in  giving  a  spotting 
correction,  which  permitted  the  firing  of  a  salvo  after  but  one 
ranging  shot. 


GUNNERY  INSTRUCTIONS. 


176 


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176 


GUNNERY  INSTRUCTIONS. 


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6     a  a  a 


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GUNNERY  INSTRUCTIONS.  177 

371.  Battle  diagram. — A  battle  diagram  (Fig.  VII)  has 
been  made  of  a  battleship  of  the  Pennsylvania  type  for  a  meau 
rauge  of  14,000  yards,  14-inch,  2,600  f.  s.  guns.  The  construc- 
tion and  study  of  such  diagrams  would  form  a  most  important 
feature  of  the  training  for  battle. 

372.  Salvo  firing  method  of  "  shorts." — Single  shots  are 
far  easier  to  spot  than  salvos.  To  spot  the  latter  successfully 
requires  much  training  and  practice.  When  a  salvo  strikes, 
the  spotter  observes  the  splashes  and  estimates  the  point  of 
mean  impact,  throwing  out  wild  shots.  He  estimates  by  the 
"  vertical  method  "  how  far  this  point  is  from  the  water  line 
of  the  target;  he  then  gives  a  spot  such  that  the  next  bunch 
will  straddle  and  fall  at  or  near  the  water  line.  He  must  im- 
mediately decide: 

(a)  The  location  of  the  mean  point  of  impact  or  center  of 
bunch  with  reference  to  the  target. 

(&)  Which,  if  any,  were  wild  shots. 

(c)  If  the  condition  of  the  sea  is  affecting  the  slick.  (See 
art.  404.) 

373.  Estimation  of  the  amount  of  spot. — The  sights  are 
regulated  by  estimating  the  percentage  of  splashes  short  of 
the  target,  and  by  keeping  the  mean  impact  on  the  target. 

374.  Mean  dispersion. — The  amount  of  dispersion  may  be 
Judged  approximately  by  estimating  the  total  dispersion  be- 
tween the  limiting  splashes  in  a  salvo,  throwing  out  wild  shots, 
and  dividing  by  three. 

375.  Chances  of  hitting. — For  theoretically  getting  the 
proper  percentage  of  shorts,  attention  is  invited  to  the  fol- 
lowing table,  based  on  the  chances  of  hitting  (see  Alger's 
Exterior  Ballistics,  Chaps.  XIII  and  XIV),  assuming  that  the 
mean  dispersion  in  range  remains  constant  at  various  ranges. 
Such  a  table  is  calculated  for  mean  dispersions  in  range  of 
40,  60,  and  80  yards,  corresponding  approximately  to  total 
dispersions  of  150,  200,  and  300  yards;  mean  impact  at  center 

34776—18 12 


178 


GUNNERY  INSTETXCTIONS. 


GUNNERY  INSTRUCTIONS. 


179 


of  djinger  space  and  at  water  line;  percentage  of  hits  to  be 
expected  and  percentage  of  short  sliots  to  attain  this  percent- 
age of  hits. 

376.  Spotting-  table— Method  of  shorts.— /.^-i/fc/i  2,900  f.  s. 
tjun,  taryct  30  feet  high  lateral  errors  not  cunsidered. 


7,000  yards . . 
10,000"  yards . 
13,000  ^•ards . 
15,000  v;irds. 
18,000  yards. 


Mean  point  of  impact  at  |  Mean  point  of  impact  at 
center  of  danger  space.  water  line. 


Percentage. 

1 

ercentagc. 

1 
1 

40 

60 

80 

40 

60 

80 

yards. 

yards. 

yards. 

yards. 

yards. 

yards. 

•i-a 

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ki 

h 

ki 

b. 

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o 

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O 

o 

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■^^    ■ 

J3 

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R 

m 

m 

J3 
CO 

50 

50 

Si 
50 

49 

S3 

50 

46 

4 

93 

12 

77 

19 

63 

14 

72 

24 

53 

30 

40 

50 

49 

50 

42 

50 

35 

25 

49 

32 

36 

37 

27 

SO 

42 

50 

32 

50 

25  ' 

29 

42 

36 

29 

40 

21 

50 

36     50 

27 

50 

21 : 

35 

31 

40 

21 

42 

16 

50 

28     50 

20 

50 

ISJ 

Danger 

space 

(yards). 


180 

108 

70 

55 

39 


Note. — These  mean  dispersions  are  less  than  ha\e  been  experienced  at  recent 
practices. 

I'lie  chances  of  liltting  ai'o  based  only  iii»<)u  vertical  errors; 
flue  to  lateral  errors  ihey  are  reduced  cdnsiderahly  on  a  short 
target. 

Assnining  the  mean  pdlnt  of  impact  on  the  target,  it  will  be 
noted  that  as  the  mean  dispersion  is  increa.sed,  the  percentage 
of  hits  decreases  very  i-apid1y. 

377.  Analysis  of  table. — From  the  table  it  is  seen  that: 

(a)  A  greater  percentage  of  shorts  is  necessary  at  high 
than  at  low  ranges. 

(b)  Where  a  mean  impact  is  some  disiauce  from  target,  an 
increase  in  dispersion  gives  more  hits.  Mathematically,  the 
mean  dispersion  for  maximum  efficiency  equals  80  per  cent  of 
distance  from  mean  point  of  impact  to  center  of  danger  space. 


180  GUNNERY  INSTRTJCTIONS. 

378.  The  advantages  of  keeping-  a  number  of  shots  short 
are: 

(a)  Fire  may  be  coutrolled  more  efficiently. 

(&)  Splashes  rising  in  the  air  will  tend  to  demoralize  enemy 
and  obscure  gun  sights. 

(c)  There  may  be  ricochet  and  under-water  hits.  Shots 
that  are  over  are  lost. 

379.  Principles  of  spotting  by  shorts.— The  following  prin- 
ciples may  be  laid  down  for  spotting  by  "shorts" : 

(«)  At  long-range  target  practice  keep  approximately  one- 
third  of  the  shots  short. 

(b)  When  a  whole  salvo  is  short  or  over  target,  give  a 
spotting  correction  at  least  equal  to  twice  tlie  estimated  mean 
dispersion  plus  distance  from  the  target  of  splash  nearest  to 
the  target. 

(c)  If  the  salvo  straddles  with  90  per  cent  of  shots  short, 
give  a  spot  "up"  of  twice  mean  dispersion;  and  with  75  per 
cent  sliort,  a  spot  equal  to  mean  dispersion ;  with  50  per  cent 
short,  malce  no  correction,  if  again  50  per  cent  are  short  give 
"up"  50  or  100. 

380.  Method  of  halving.— In  combination  with  the  method 
of  "shorts,"  corrections  are  sometimes  made  on  the  principle 
of  "halving."  In  getting  on  the  target,  after  a  first  spot  each 
correction  is  halved  until  the  salvo  is  brought  on.  For  ex- 
ample, first  salvo  all  over  700  yards,  spot,  "Down  400,"  second 
salvo,  over,  one-half  of  first  correction  or  "Down  200,"  third 
salvo  on  the  water  line.  With  the  rate  of  change  constant,  the 
spotter  is  absolutely  sure  to  get  "on"  in  time  with  this  method 
which,  however,  is  slow. 

381.  Selection  of  spotters.— If  practicable,  the  chief  spottei- 
ought  not  to  have  a  turret;  other  spotters  should  not  have 
duties  which  will  interfere  with  their  training  and  work  in 
battle.  In  making  battery  assignments  consider  what  officers 
may  be  selected  as  spotters,  and  if  they  are  given  turrets  de- 
tail junior  officers  who  can  take  charge  of  the  division  in 


GUNNERY  INSTRUCTIONS.  181 

their  absuiice.  With  tlie  exception  of  the  four  senior  olUcers 
in  a  battlesliip  it  is  proper  to  assign  any  officer  as  spotter  who 
lias  demonstratetl  liis  excellence. 

382.  In  selecting  spotters  the  following  are  suggested: 
(<;)  Only  coninilssiuned  ollicer.s  .slunthl  act  a.s  spotter.s.  (b) 
Note  records  as  spotters  in  previous  practices,  (c)  Have  eyes 
of  candidates  examined  and  require  normal  vision,  (d)  The 
natural  (pialities  to  be  desired  in  a  spotter  are  even  di.spo- 
sUiou.  quick  judgment,  conlidence,  coolness,  keenness,  and 
intelligence  under  adverse  conditions;  courage  of  his  convic- 
tions at  all  times,  (e)  A  spotter  should  have  a  knowledge 
of  g\innery  including  ballistics',  and  the  theory  ;ind  practice 
of  fire  control. 

METHODS  OF  TRAINING. 

383.  Officer  in  charge  of  training. — The  training  of  spot- 
ters should  be  under  the  supervision  of  the  gunnery  officer, 

384.  Essentials  in  training.— (a)  Require  spotters  to  con- 
struct necessary  diagrams,  (b)  Hold  meetings  for  discussion 
of  spotting,  calculation  of  initial  sight-bar  rauge,  errors  of  gun 
lire,  and  a  general  exchange  of  ideas,  (c)  Outline  scheme  of 
spotting  drills  and  keep  up  drills  throughout  the  year  even  for 
experienced  spotters,  (rf)  Never  criticise  a  spotter  in  action; 
any  confusion  will  ruin  a  performance.  After  a  drill  or  prac- 
tice, mistakes  should  be  carefully  pointed  out.  (e)  Give 
spotters  every  opportunity  to  practice  and  observe  the  fire  of 
other  slnps.  (/)  It  is  desirable  to  train  certain  spotters  for 
high  and  others  for  low  spotting  positions. 

385.  Training  devices. —  («)  The  fundaiiiental  principle  of 
any  device  for  training  spotters  is  that  it  should  be  realistic. 
Any  device  by  which  a  small  object  is  projected  toward  a  tar- 
get simulating  a  projectile  will  permit  an  interesting  and  in- 
structive form  of  drill. 

(6)  The  spotting  board  or  range  should  be  as  long  as  con- 
ditions will  permit. 


182  GUNNERY  INSTRUCTIONS. 

(c)  The  target  and  height  of  the  spotter's  eye  should  be  in 
rlie  same  reduced  proportion  as  tlie  actual  range  is  to  the 
spotting  range.  Never  increase  size  of  target  to  represent 
magnified  image,  as  it  destroys  the  true  perspective. 

386.  Preliminary. — In  the  beginning  set  up  a  target  to 
scale.  Witii  a  wand  point  to  the  target,  indicating  hits  and 
misses.  Spotters  note  how  much  the  projectile  missed  the 
target  and  give  correction.  These  drills  should  be  held  until 
spotters  can  quicldy  and  accurately  give  a  spot.  Diagrams 
for  different  calibers  and  ranges  posted  in  a  spotter's  room 
will  aid  in  keeping  in  mind  the  proportion  of  target  and  spot- 
ting data. 

387.  Training  for  night  practice. — The  training  for  spotting 
for  night  practice  at  short  range  is  carried  along  the  same 
lines  as  for  day.  With  diagrams  previously  prepared  and 
studied  a  target  is  set  up  on  deck  at  as  long  a  range  as  possi- 
ble. The  target  is  illuminated  by  a  bull's-eye  lantern.  For 
simulating  tracers,  a  wand  is  used,  on  the  tip  of  which  is 
placed  a  3-candlepower  light.  This  may  be  turned  on  or  off  to 
simulate  a  tracer  passing  over  target.  During  the  day  the 
wardroom  may  be  darkened  and  a  similar  range  laid  out  20 
yards  long  with  target  built  to  scale,  and  drill  conducted  in 
the  same  manner.  All  persons  who  may  be  called  upon  to 
control  torpedo-defense  guns  should  be  given  this  training, 

388.  Training  for  long-range  spotting. — Division  officers 
to  train  for  spotting :  Require  all  division  officers  to  train  for 
spotting  in  order  that  they  may  prepare  themselves  and  petty 
officers  for  independent  control.  Never  hold  a  drill  without  a 
number  of  officers  present.  Keep  and  publish  records  weekly. 
Encourage  competition  in  spotting. 

389.  Training  for  long-range  spotting  is  conducted  as  fol- 
lows by:  (1)  Drill  at  the  spotting  board.  (2)  Drill  on  spot- 
ting range  aboard  ship.  (3)  Subcaliber  practice.  (4)  Obser- 
vation of  practices.  (5)  Spotting  practice.  (6)  Spotting  at 
battle  practice. 


GUNNERY  INSTRUCTIONS.  183 

390.  Spotting  board.— A  spottins  boaixl  is  a  device  by  which 
long-rauge  firing  may  be  simulated  upon  a  small  scale,  for  the 
training  of  spotters.  While  the  details  of  spotting  boards 
vary,  the  following  general  principles  of  construction  are  com- 
mon to  all:  (a)  The  scale  upon  which  a  board  is  constructed 
is  the  ratio  of  the  length  of  the  board  to  the  range,  (b)  The 
dimensions  of  target,  splashes,  height  of  spotters,  and  horizon 
on  the  spotting  board  bear  this  same  ratio  in  comparison  to 
the  actual  heights,  etc.  (c)  The  general  perspective  must 
remain  the  same  as  at  the  long  range. 

391.  Dimensions. — Board  to  represent  a  range  of  10,000 
yards  for  12-inch  guns  firing  at  a  target  30  by  GO  feet.  High 
spotting  position,  120  feet.  Low  spotting  position,  50  feet. 
Splashes,  mean  height,  173  feet;  diameter,  20  feet.  Eye  to 
target,  30  feet.  Scale  of  board,  1/1000.  Target  dimensions, 
0.36  by  0.72  inch.  Height  of  eye-high  position,  1.2  inches; 
height  of  eye-low  position,  0.3  inch,  considering  earth  curva- 
ture. Mean  dimensions  of  splashes,  2.1  by  0.48  inch.  50  yards 
on  board  equals  1.8  inches. 

392.  Drill  at  the  spotting  board. — Before  the  drill  hour 
place  spotting  board  where  the  light  is  good,  little  confusion, 
and  no  interruptions  likely.  Lay  off  a  distance  of  30  feet 
from  target ;  at  this  mark  place  a  rest  for  a  3-power  glass  so 
that  the  eye  of  the  spotter  will  be  about  1.2  inch  above  the 
plane  of  the  board.  In  a  new  ship  start  drill  with  the  board 
as  soon  as  officers  are  settled  in  their  duties.    Give  all  officers, 

,  from  gunnery  officers  down,  drill  at  spotting.  At  first  spot 
single  shots,  next  salvos.  In  an  hour  15  officers  can  spot  two 
strings  apiece,  and  at  least  this  number  should  be  given.  Hold 
drill  five  times  a  week. 

393.  Procedure. — Before  each  drill  arrange  what  splashes 
are  to  be  used  for  the  strings.  Before  each  string,  the  spotter 
should  study  the  appearance  of  shots  short  and  over  1.000, 
500,  200.  and  0  yard.  From  this  practice  will  be  learne<l  the 
ratio  between  the  height  of  the  target  and  that  of  the  point 


184  GUNNERY  INSTRUCTIONS. 

of  fall.  Two  officers  are  required  to  operate  the  splashes,  and 
one  to  act  as  recorder.  In  turn  each  officer  spots  his  two 
strings  and  his  spots  are  recorded.  The  number  of  spots  to 
get  "  on,"  and  his  error  are  determined. 

EXAMPLES. 

(a)  First  string — Single  shots.     (Distance  from  water  line.) 

No.  1.  1,500  short. 

No.  2.  1,000  over.  (Shows  disadvantage  of  ranging  shot 
that  is  far  over.) 

No.  3.  1,000  short. 

No.  4.  0  and  10  L  in  deflection.  (Shows  difficulty  of  spot- 
ting range  and  necessity  of  spotting  on  in  deflection.) 

No.  5.  100  short  and  10  R.  (Shows  difficulty  of  spotting 
range  and  necessity  of  spotting  on  in  deflection.) 

No.  6,  150  over  and  behind  target,  just  beyond  danger  space ; 
usually  spotted  a  hit,  danger  of  "  overs." 

No.  7.  50  short  and  4  knots  left,  range  spot  in  doubt.  A  fine 
ranging  shot  if  deflections  were  correct. 

No.  8.  2(X)  over  and  2  knots  right,  a  good  "  over "  ranging 
shot  to  spot  "  on  "  in  range  and  deflection. 

No.  9.  500  short  and  in  front  of  target,  usually  underspotted. 

No.  10.  100  short  and  in  front  of  target,  usually  overspotted 
but  a  good  ranging  shot. 

(b)  Second  siring. — Salvos.     (Assume  mean  dispersion  equal 
to  one-third  of  distance  between  limiting  splashes.) 

No.  1.  4  splashes,  "  on,"  200  yards  between  limiting  splashes. 
Good  salvo,  less  than  average  dispersion. 

No.  2.  4  splashes,  "  on,"  50  yards  between  limiting  splashes. 
Excellent  salvo. 

No.  3.  4  splashes,  "  on,"  500  yards  between  limiting  splashes. 
Large  dispersion,  ^ect  on  hits. 


GUNNERY  INSTRUCTIONS.  186 

No.  4.  4  splashes,  500  over,  3  splashes  bunched,  1  splash  50 
yards  short.  Short  shot  wild,  spotter  apt  to  give  no  correc- 
tion as  he  has  25  per  cent  of  splashes  short. 

No.  5.  4  splashes,  1,000  yards  short,  250  yards  between  lim- 
iting splashes.  (Splashes  in  line.)  Difficulty  in  spotting 
splashes  in  line. 

No.  6.  4  splashes,  200  yards  over,  5  knots  left,  200  yards 
between  limiting  splashes.  Error  in  deflection  may  cause 
error  in  spotting. 

No.  7,  6  si)lashes,  2  .splashes  100  yards  short,  4  splashes 
bunched  300  yards  over,  2  shots  wild,  spotter  apt  to  give  "  no 
correction." 

No.  8.  6  splashes,  300  yards  short,  50  yards  between  limit- 
ing .splashes.  Small  dispersion.  Easier  spotting.  Necessity 
for  accurate  spotting. 

No.  P.  0  splashes.  300  yards  over,  .50  yards  between  limit- 
ing splashes,  necessity  for  accurate  spotting. 

No.  10.  6  splashes,  200  yards  short,  500  yards  between  limit- 
ing splashes.    Hits  under  these  conditions  were  at  random. 

These  two  strings  illustrate  some  of  the  vmderlying  prin- 
ciples of  spotting.    Z\Iany  others  may  be  arranged. 

394.  Spotting-board  problems.- — Innumerable  problems  may 
be  worked  out  on  the  spotting  board  in  connection  with  fire- 
control  drills,  such  as  spotters  giving  corrections  to  fire-control 
party,  determined  from  previously  worked-out  conditions; 
determination  of  number  of  shots  or  salvos  to  get  "  on  "  tar- 
get ;  control  of  mixed  caliber  salvos ;  concentration  of  two 
ships  and  control  of  salvos  by  two  spotters ;  rate  of  change 
of  range ;  and  change  incidental  to  enemy  or  own  ship  chang- 
ing course. 

395.  Spotting  range. — For  advanced  training  the  spotting 
range  is  better  than  the  spotting  board.  Select  a  clear  line  of 
sight  along  the  deck.  Heat  waves  and  curvature  of  the  deck 
may  cau§e  difficulties.  As  long  a  distance  as  possible  is  de- 
sirable ;  a  fair  average  is  250  feet.    Let  200  feet  equal  a  mean 


186  GUNNERY  INSTRUCTIONS. 

range  of  14.000  yards,  12-inch  guns,  target  30  by  60  feet,  spot- 
ters 120  and  60  feet  high  (effective  height,  82  feet  and  12 
feet)  :  Target,  5.2  by  10.4  inches;  spotter  (high),  4.7  inches; 
spotter  (low),  0.7  inch;  splashes,  10  by  1  inch;  50  yards= 
8.6  inches. 

396.  Details  of  range.— At  one  end  of  the  range  place  a 
rest  for  the  spotter's  glasses  about  4  inches  high,  correspond- 
ing to  high  spotting  position.  At  200  feet  from  this  point 
mark  the  position  of  the  target.  Lay  off  2,000  yards  in  front 
of  and  behind  the  target.  Between  500  short  and  500  over, 
divide  into  50-yard  intervals ;  then  up  to  1,000  yards,  in  100- 
yard  intervals.  From  1,000  to  2,000  short  or  over  in  200-yard 
intervals.  In  order  to  quickly  lay  off  these,  mark  them  on  a 
canvas  scale  about  40  feet  long.  With  this  laid  flat  on  the 
deck,  and  zero  corresponding  to  the  position  of  the  target,  the 
target  and  splashes  can  be  easily  placed.  Make  the  target  of 
mosquito  cloth  to  simulate  a  net  screen,  or  of  tin,  to  resemble 
the  outline  of  a  battleship  and  mount  it  so  it  will  stand 
upright. 

It  is  necessary  to  have  about  50  splashes.  They  may  be 
made  out  of  cardboard  of  various  but  proper  shapes,  about  10 
inches  high  and  1  inch  wide,  mounted  and  hinged  on  thin 
metal  bases.  On  the  foi'ward  side  of  each  an  elastic  band  is 
so  secured  that  the  splash  will  naturally  lie  flat ;  on  the  after 
side  through  fair  leads  a  line  is  made  fast  which  leads  to  a 
position  from  where  the  splash  operator  can  not  be  observed. 
On  a  wire  a  curtain  is  run  In  such  a  way  that  the  spotter  will 
not  see  the  splash  operators. 

397.  Drill  on  range. — To  hold  a  drill,  decide  upon  the  prob- 
lem to  be  solved,  conditions,  etc.  Have  splashes  put  in  position 
so  that  the  shots  and  salvos  may  be  used  as  required  by  prob- 
lem. A  detail  will  be  require(3  to  operate  splashes  under  the 
supervision  of  an  officer. 

Examples. —  (a)  First  string:  Fire  two  ranging  shots  and 
eight  salvos.     At  zero  minutes  fire  a  blank  cartridge;  after 


GUNNERY  INSTRUCTIONS.  187 

about  20  seconds  a  ranj^ing  splasli  rises,  subsiding  in  15  sec- 
onds ;  at  40  seconds  fire  anotlier  ranging  shot,  which  is  seen  20 
seconds  later,  etc. ;  at  1  minute  20  seconds  fire  a  salvo  of  four 
guns  and  continue  at  intervals  until  the  last  salvo  has  been 
spotted.  Several  officers  spot  and  independently  record  their 
results. 

(b)  Second  string:  Give  each  spotter  two  ranging  shots  and 
five  salvos  to  determine,  first,  how  quickly  he  can  get  on ; 
second,  how  well  he  can  keep  on. 

(c)  Third  string:  Devise  a  problem  and  use  spotting  range 
in  connection  with  whole  fire-control  system  of  ship.  Here 
with  three  scales  for  ranges  of  10,000,  12,000,  and  14,000 
yards  laid  side  by  side  and  painted  red,  white,  and  blue,  and 
several  targets  of  proper  sizes,  the  battle  range  may  be  quickly 
(;hanged  and  a  new  target  used.  This  is  necessary  to  simulate 
ranging  shots  at  about  16,000  yards,  the  range  closed,  and 
.salvos  operated  at  a  closer  distance.  Figure  VIII  shows  ar- 
rangement of  target  splashes,  scales,  etc. 

398.  Subcaliber  practice. — At  ranges  at  which  angles  of  fall 
are  equal  to  those  of  the  larger  guns,  excellent  spotting  prac- 
tice may  be  had.  The  spotter  must  be  at  a  height  propor- 
tional to  the  range;  the  target  should  be  in  proportion,  and 
paper  range  strips  made  so  that  the  shots  will  follow  the  spot- 
ter's corrections.  Require  the  spotters  to  send  spots  to  the 
subcentral  and  to  control  the  regular  fire-control  lines. 

399.  Spotting  with  reduced  charg'es. — Unless  there  is  an 
understanding  between  the  spotter  and  the  fire-control  party, 
there  is  likelihood  of  errors  being  introduced  when  using  re- 
duced charges.  In  using  reduced  charges,  if  a  shell  lands  200 
yards  short  a  spot  of  "  up  200  "  is  converted  to  the  proper 
sight  correction  in  the  subcentral  before  it  is  applied  to  the 
sight-bar  range,  and  sent  to  the  guns.  A  simple  way  to  avoid 
error  is  to  have  the  clocks  and  dials  in  the  subcentral  set  for 
the  actual  range,  and  with  the  dials  in  the  subs  marked  with 


188  GUNNERY  INSTRUCTIONS. 

rjinges  I'or  the  reduced  velocity.  Anotiier  method  is  to  make 
a  drawing  of  proper  size  of  the  sight  strips  for  the  guns  to  be 
tired,  malting  the  graduations  and  lettering  correspond  to  the 
('(irrect  angles  of  departure  for  the  new  initial  velocity.  Make 
blue  prints  of  this  drawing  and  carefully  paste  them  over  the 
siglit  strips;  then  boresight  and  shift  tlie  strips  with  blue 
prints  attached,  as  necessary.  No  conversion  of  actual  range 
is  now  necesary  (i.  e.,  the  spot,  or  the  range  finder  reading) 
to  sight  bar  range,  a-nd  in  consequence  there  is  no  loss  of  speed 
or  accxiracy. 

400.  Spotting  practice.— Just  before  spotting  practice  the 
final  selection  of  spotters  is  made;  two  being  particularly 
trained  for  high  and  two  for  low  control.  Each  spotter  at 
this  time  spots  under  conditions  somewhat  similar  to  those 
of  battle  practice,  and  experiences  difficulties  incident  to 
smoke,  gases,  sun.  refraction,  mirage,  etc. 

401.  Observation  of  other  ships. — A  spotter  should  be  given 
every  opportunity  to  observe  the  fire  of  other  ships.  At  such 
times  he  must  record  each  spot  and  make  notes,  and  after- 
wards compare  his  record  with  the  results  reported  by  the 
observers. 

Discussions  witli  other  spotters  and  exchange  of  ideas  at 
these  times  will  be  very  instructive. 

402.  Keep  the  following  points  in  mind  (elementary  prac- 
tice) : 

(1)  In  spotting  the  first  shot  give  the  full  correction. 

(2)  After  the -first  shot  do  not  correct  until  two  shots  have 
gone  in  practically  the  same  place. 

(3)  Be  on  the  safe  side  and  under  spot.  Do  not  give  a 
correction  after  each  shot.  Good  pointing  is  what  produces 
a  good  score  at  this  practice.  Without  good  pointing  satis- 
factory results  can  not  be  obtained,  and  spotting  will  not  help 
the  performance.  After  the  first  shot  is  spotted  "  on  "  gener- 
ally further  corrections  on  a  run  should  be  unnecessary. 


GUNNERY  INSTRUCTIONS. 


189 


190  GUNNERY  INSTRUCTIONS. 

(4)  Keep  out  of  wind,  be  protected  from  rain,  keep  warm 
and  clear  of  confusion,  malce  yourself  comfortable. 

(5)  Give  corrections  quickly  and  distinctly;  make  no  com- 
Tnents. 

(6)  Look  out  for  shells  passing  through  holes  in  target. 
Accurate  spotting  in  such  cases  will  bring  hits  to  a  ship  which 
may  otherwise  be  counted  misses. 

(7)  Be  prepared  to  spot  by  the  "splash  method." 

(8)  If  on  one  run  or  at  one  gun  something  goes  wrong  do 
not  carry  error  over  to  the  next  run  or  gun. 

(9)  Be  sure  that  system  of  communication  is  efficient  and 
that  there  will  be  no  confusion  in  transmitting  spots. 

(10)  Be  sure  that  a  sight  correction  will  always  be  applied 
before  subsequent  shots  are  fired. 

(11)  Look  out  for  spotting  with  a  following  wind.  It  may 
be  bad  for  both  pointers  and  spotters. 

(12)  The  most  favorable  weather  conditions  are  wind  on 
engaged  bow,  force  3-4,  and  sun  behind  the  .spotter. 

403.  Night  target  practice. — Low-control  spotters  should 
keep  near  firing  guns.  The  important  point  in  selecting  a  posi- 
tion is  to  be  clear  of  smoke,  gases,  and  blast.  Keep  shots 
clear  of  the  .side,  edges,  and  the  top  of  the  target.  High  spots 
are  particularly  deceptive.  The  spotter,  pointer,  and  search- 
light operator  must  all  simultaneously  have  a  good  view  of  the 
target. 

404.  Target  practice,  long  range.— Many  of  the  points  men- 
tioned in  article  402  apply.  Spotting  at  a  net  screen  is  difficult 
because  of  lack  of  opaqueness.  When  a  straddle  is  obtained 
a  spotter  in  a  low  position  can  control  the  fire  quite  efficiently. 
Once  "on"  in  target  practice  do  not  attempt  to  give  a  spot- 
ling  correction  for  each  salvo ;  the  fire  should  be  rapid  to  be 
effective.  Be  Very  careful  in  working  out  the  initial  deflection. 
If  the  first  shot  is  wide  in  deflection  spot  on  in  deflection,  and 
come  down  in  range  unless  the  range  is  manifestly  short. 
Take  into  consideration  the  height  and  character  of  the  sea. 


GUNNERY  INSTRUCTIONS.  191 

An  impact  on  the  crest  of  a  sea  while  the  target  is  in  a  trough 
may  give  an  erroneous  impression.  When  once  "  on  "  give  a 
spot  up  or  down  50  or  100  in  order  to  make  sure  of  conditions 
and  as  a  check. 

405.  Hints  in  long'-range  firing. —  (1)  Before  the  ship  opens 
fire  the  spotter  should  see  that  all  turrets  are  trained  on  the 
proper  target.  Neglect  of  this  precaution  lias  occurred  and 
resulted  in  reducing  the  firing  ship's  score  and  endangering 
other  ships. 

(2)  The  spotter  should  spot  the  shots  back  and  forth  across 
the  target  until  he  knows  that  he  is  getting  hits.  The  most 
frequent  luistake  is  for  .spotters  to  think  that  the  shots  are 
hitting  wlien  actually  tliey  are  just  short  or  over.  But  when 
once  he  is  sure  of  being  "  on  "  he  should  not  spot  unnecessarily 
as  this  slows  the  firing  and  may  introduce  errors. 

(3)  Be  very  careful  to  spot  the  deflection  at  the  instant 
the  shots  land. 

(4)  Between  salvos  watch  the  bow  wave  of  the  target,  the 
wake  and  bow  wave  of  the  towing  ship,  and  the  bearing  of 
objects,  such  as  the  ends  of  the  bridge  or  the  two  boat  cranes 
on  towing  ship.  Changes  of  speed  and  changes  of  course  can 
be  detected  in  this  way,  and  this  information  will  be  of  great 
assistance  to  the  tracking  party  and  to  the  spotter. 

(5)  If  .spotting  explosive  shells  the  dark  gases  given  oft:" 
at  detonation  will  cause  the  splashes  to  look  like  hits,  and 
the  spotter  should  be  positive  that  the  salvos  are  hitting. 

(6)  If  firing  ship  is  turning,  the  deflection  can  not  be 
spotted  correctly  until  the  ship  is  steady  on  the  new  course. 

406.  Two  or  more  calibers  fired  together. — It  is  impracti- 
ticable  at  battle  ranges  to  distinguish  the  splashes  of  turret 
guns  of  one  caliber  from  those  of  another  caliber,  striking  at 
the  same  time.  In  order  therefore  to  get  accurate  spotting  of 
the  shots  of  a  ship  having  guns  of  two  or  more  calibers,  it  is 
desirable  to  arrange  the  fire  so  that  the  shots  from  the  differ- 
ent calibers  will  not  land  together. 


192  GUNNERY  INSTRUCTIONS. 

407.  Trial  shots.— To  assist  tlie  spotter  in  getting  on 
(iniokly,  it  is  desirable  before  a  battle  practice,  to  fire  trial 
shots  from  each  caliber  of  gun  that  is  to  fire.  All  of  the  shots 
of  a  caliber  should  be  fired  with  the  sights  set  alike  on  all 
rounds  fired.  During  the  firing  all  range  finders  should  take 
i-eadiugs  of  the  range.  From  the  mean  point  of  impact  of 
trial  shots  the  error  between  the  range  finder  and  the  sight 
bar  can  be  established.  Turret  officers  and  others  should  take 
advantage  of  these  shots  to  practice  spotting  from  what  will 
be  their  battle  stations.  Every  care  should  be  taken  in  mak- 
ing allowance  for  temperature  of  powder,  erosion,  density, 
of  air,  etc.,  to  laud  the  trial  shots  as  close  as  possible  to  the 
target.  It  must  be  clearly  understood  that  on  subsequent 
days  a  large  error  may  exist  between  the  range  finder  and  the 
sight  bar  due  to  different  atmospheric  conditions  or  other 
causes,  and  the  spotters  should  be  prepared  for  these  varia- 
tions if  they  are  found.  Trial  shots  are  especially  desirable 
for  shi])s  having  two  or  more  calibers. 

408.  Hints  on  firing  trial  shots. —  (a)  Land  first  .shot  as 
near  target  as  possible. 

( 6 )  If  the  first  shot  lands  near  the  target  do  not  change  the 
sight  bar.  If  it  lands  more  than  300  yards  from  the  target 
change  the  range  to  reduce  the  error  to  zero  and  fire  subse- 
quent shots  without  further  change  of  sight  bar. 

(c)  If  it  is  necessary  to  change  the  sight  setting  require  a 
report  that  the  change  has  been  made  before  permitting  the 
next  shot  to  be  fired. 

(d)  If  four  shots  are  fired,  or  if  three  are  fired  and  the  first 
shot  appears  to  be  unreliable,  throw  out  the  first  or  cold  shot 
in  averaging  the  results. 

(e)  Record  the  positions  of  cross  wires  on  target  for  each 
shot  and  if  check  telescopes  are  available,  station  an  officer  at 
them  to  get  this  data. 


GUNNERY  INSTRUCTIONS.  193 

(/)  Make  ciirelul  uliservutions  of  wind  iuid  transfer  the 
splash  (if  each  shot  to  its  proper  position  relative  to  the  target 
had  il  been  fired  in  a  cahn.     Check  drift. 

{(I)  Take  raii.ue  linder  readings  during  (lie  tiring  and  plot 
tlieui  to  give  a  range  curve,  tlien  pick  tlie  range  finder  range 
for  each  shot  from  this  curve. 

(h)  Take  range  readings  from  all  other  range  tinders,  plot 
their  curves  and  deternune  separately  the  error  of  each  from 
the  standard  range  finder. 

(i)   Record  the  sight  setting  before  and  after  each  shot  fired. 

(j)  Be  sure  that  all  observers  know  just  what  data  is  to  be 
taken  and  how  reported  to  the  firing  ship. 

(k)  Select  the  best  and  most  reliable  pointers  to  fire  and 
allow  plenty  of  time  for  them  to  get  "on"  and  fire. 

(/)  Be  sure  they  understand  that  they  must  be  exactly  on 
and  that  the  sights  will  be  set  to  land  the  shot  near  but  not  to 
hit  the  target.. 

(/»)  Test  and  check  the  boresighting  both  before  and  after 
the  firing.  Test  for  parallax,  lost  motion,  inaccuracies  in  bore- 
sight  telescopes,  and  nonrigidity  of  parts. 

(n)  Do  not  fire  all  shots  at  a  very  high  range,  9,000  to 
10.000  yards  should  be  sufficient  if  the  allowance  of  ammuni- 
tion is  small. 

(p)  Require  spotters  and  turret  officers  to  exercise  at  spot- 
ting from  regular  stations  during  the^firing  but  do  not  make 
a  spotting  practice  of  it  by  changing  the  range  after  each  shot. 

(q)   Select  smooth-water  conditions. 

(r)  Collect  data  regarding  shell  seating,  recoil  of  guns,  kick 
of  turrets,  etc. 

409.  Ranging  shots. — Experience  has  demonstrated  that  it 
is  nuich  easier  to  spot  a  single  shot  than  to  spot  a  salvo.  For 
this  reason  single  guns  are  preferred  for  ranging.  In  ranging 
guard  againt  inaccurate  pointing.  The  spotter  must  at  all 
times  have  clearly  in  mind  that  the  gun,  even  when  correctly 

34776—18 13 


194  GUNNERY  INSTRUCTIONS. 

jtoiuted.  will  have  considerable  dispersion  and  due  coj^iiizance 
of  this  imist  l)e  talieii  in  noting'  the  fall  of  siil>sequent  I'angiug 
shots. 

It  is  pidliahly  'hetlcr  in  all  cases,  using  every  available 
means  and  data  at  hand,  to  tire  to  hit  the  target  on  the  first 
sliol.  .Most  spoitt'cs  ])rcfci'  lo  have  r;iiiging  sliots  sliort, 
as  it  i>-.  in  general,  easier  to  estimate  slan-ts  liian  overs; 
consequently,  some  ships  purposely  endeavor  to  tlirow  the 
ranging  shots  short.  This  might  be  desirable  were  it  possible 
to  always  coiiirol  llic  fire  so  as  to  throw  the  lirst  shot  IdU  or 
liU(»  yai-ds  shoit.  but  so  many  errors  are  always  present  that 
tiiere  is  no  absolute  assurance  as  to  exactly  where  the  first 
shot  will  land,  and  a  ranging  shot  landing  some  distance  from 
the  tnrgei  will  delay  considerably  the  salvos. 

410.  Error  in  rate  of  change. — Witli  a  wi-ong  rate  of  change 
it  is  almost  impos.sible  for  the  spotter  to  get  or  keep  the  shots 
on  the  target.  The  spotter  should  not,  ordinarily,  attempt 
lo  coruMt  f<ii-  the  rate  of  change,  but  this  correction  should 
be  made  in  tlie  subcentral.  The  spot  sent  to  tlie  snbcentral 
should  always  indicate  the  actual  correction  that  sliould  be 
applied  to  bring  the  shots  on  the  target.  If  the  shots  per- 
sistently fall  short  or  over  the  target,  it  shonld  be  evident  in 
the  subcentral  that  tlie  rate  of  change  is  wrong,  and  the  rate 
should  be  corrected.  With  no  system  provitled  for  l<;eeping 
the  rate  of  change  ol^  range,  the  person  controlling  the  fire 
of  guns  must  allow  for  the  rate  of  change  in  giving  spots. 
If  ai)proaching  the  target  make  tlie  "down  "  spots  nulical,  if 
re<-eding  from  the  tai'get  be  sure  to  make  the  "up'"  spots 
sufficient. 


CHAPTER  IT. 
PROBLEMS  IN  FIRE  CONTROL  AND  CALIBRATION. 

411.  Character  of  problems. — Tlic  lollowiiiu-  nine  problems, 
witli  sdlntions.  liaxe  been  supplied  by  the  department  of  orrt- 
ujince  :in(l  .mmnery  at  tlie  Navy  Academy.  They  furnish  a 
;j,(iid(>  to  the  solution  of  problems  of  iiractical  gunnery,  in- 
volving- the  use  of  range  table  data. 

412.  Problem  1. — Four  shots  wci-e  bred  on  ( iililn-ation 
practice  from  a  12-inch  gun,  initial  velocity  2,700  foot-seconds, 
weight  (tf  shell  870  pounds,  inider  the  following  conditions : 

Actual  distance  of  target  from  tiring  vessel  7,500  yards; 
height  of- center  of  bull's-eye  above  water  level  10  feet;  sight 
of  gun  set  for  7,500  yards;  bearing  of  target  from  ship,  north 
(Irui'l:  wind  from  soutlnvest  (true),  velocity  15  jcnots  per 
hour:  barometer  30..50  inches;  tliermometer  (temperature  jiir) 
00°  F. :  temperature  of  powder  100°  F. ;  weight  of  shell  870 
pouiKls  (standard).  Owing  to  lack  of  skill  in  the  pointer 
each  shot  was  bred  with  the  cross  wires  of  the  telescopes  8 
feet  above  the  ci'nier  of  the  bull's-eye. 

Measured  from  the  foot  of  the  perpendicular  to  the  water 
through  the  center  of  the  target  the  shot  fell  as  follows: 

iNo.  1.  .3.50  yards  over,  15  yards  right;  No.  2,  150  yards  over, 
85  yartls  right  ;  No.  3.  200  yards  over.  20  yards  right;  No.  4, 
;:'>00  yards  over.  30  yards  right. 

Find  the  mean  error  of  the  gun  under  standard  conditions 
in  range  and  deflection  and  the  mean  dispersion  in  range  and 
('cMection. 


196 


GUNNERY  INSTRUCTIONS. 


No.  of  shot. 

Fall  in  range 
(yards). 

Fall  in  deflection 
(yards). 

Over. 

350 
150 
200 
300 

Short. 

Right. 

Left. 

1..     . 

15 
35 
20 
30 

2 

3                                         .       . 

^ 

4)1,000 

4)100 

^^e;^l  i)()iut  of  impact  250  yards  over,  25  yards  right.  Cor- 
rection tor  10  feet  heiirht  of  center  of  l)uirs-eye.  from  range 
table  column  7.  55  yards. 

JfO./ 


GUNNERY  INSTRUCTIONS.  197 

Observed  mean  error.  In  niiiLif.  11).")  y;ir(ls  <)\<t:  in  ilctlcc- 
(ion,  25  yards  rijilil. 

It  is  to  be  noted  ilial  llie  ol»sei-ved  iiieiin  cmtot  in  ruuge  as 
Just  found  contains  elements  of  error  in  range  i)roduced  by  the 
following  causes:  (1)  Wind  component  in  the  jilane  of  hre; 
(2)  variation  of  weight  of  shell  from  standar<l  weight;  (3) 
variation  from  standard  density  of  Ihc  air;  (4)  variation 
from  standard  temperiiture  of  the  powder;  and  (5)  cross 
wires  not  being  on  (-(Mitei-  of  bull's-eye  at  the  instant  the  shot 
was  firetl. 

TO   CORRECT   OBSERVED   ERRORS   FOR   VARIATIONS 
FROM  STANDARD  CONDITIONS. 

Range  Corrections. 

Note. — All  data  from  range  tables  compu1(>d  for  range  of 
7.500  yards. 

1.  Wind  coniponent  in  line  of  fire. — Oonii">nent  of  wind  in 
Hue  of  fire  is  15 X cos.  45°.  knots=10.6  knots. 

From  the  range  table,  column  13,  a  12-knot  wind  in  tlie 
plane  of  fire,  if  blowing  with  the  shell,  would  increase  the 
range  15  yards.  Hence  the  present  wind  would  increase  the 
range  15/1 2 X cos.  45X15=13.3  yards. 

2.  Change  of  range  due  to  variation  of  weight  of  shell.— 
In  this  ca.se.  the  shell  being  of  standard  weight,  the  change  of 
range  due  to  this  element  would  be  0  yards. 

3.  Change  of  range  due  to  density  of  air. — From  Table  II. 
page  165,  Alger's  Exterior  Ballistics,  the  density  of  tlie  air  for 
temperature  60°  V.  and  barometer  30..50  inches  is  1.031  or  3.1 
per  cent  greater  than  standard.  Tlie  ]-ange  tables  are  based 
upon  temperature  59°  F.  and  29.53  barometer. 

From  the  range  tables,  column  12,  an  increase  of  10  per 
cent  in  density  woidd  shorten  the  range  122  yards.    Therefore, 


198 


GUNNERY  INSTRUCTIONS. 


the  decrease  in  range  due  to  3.1  per  cent  increase  in  density 
of  air=122/10X  3.1=37.8  yards. 

4.  Chang-e  of  range  due  to  temperature  of  powder. — From 
tlic  ransie  tables,  column  10,  tlie  standard  tem]teratiire  of  tin- 
powder  is  90°  F..  and  an  increase  of  10°  in  the  temperature 
would  increase  the  muzzle  velocity  by  3.")  foot-seconds.  It  is 
also  noted  in  range  tables  that  a  change  in  uuizzle  velocity 
(if  50  foot-seconds  would  change  the  range  215  yards.  Hence. 
increase  in  nuizzle  velocity  is  35/lOX  (100-90)  =35  foot-sec- 
onds, and  increase  of  range  due  to  this  inci-ease  of  nnizzl<> 
velocity  will  be  215/50X35=150.5  yards. 

5.  Correction  for  point  of  aim. — From  the  tables  again, 
colunm  19.  the  increase  of  range  due  to  raising  the  point  of 
impact  18  feet  is  100  yards.  Therefore  the  increase  due  to 
aiming  3  feet  high  is  100/18X3=16.7  yards. 

0.  Summary  of  correction  for  range.— Compared  to  the 
range  of  a  standard  shell,  the  shots  tired  under  the  conditions 
of  the  problem  would  fall,  for  each  variation  in  conditions, 
as  follows: 


Yards. 


Over. 


Wind. 


13.3 


Weight  of  shell 

Ocnsityofair. , 

Temperature  of  powder ^^"-  ^ 

Krror  in  aim ^"" ' 


Sum . 


180.  .5 


Short. 


37.8 


37.8 


Yards 
over. 


Correclion  to  moan  observed  error  in  range= 
Mean  observed  error  in  range 


^difference 142. 7 

195.0 


True  mean  error  in  range  (imder  standard  conditions) •   ••>2- 3 


GUNNERY  INSTRUCTIONS.  199 

7.  To  correct  the  observed  mean  error  in  deflection. — liy 
siiiiihii-  process  from  riiiiiiv  taltlc.  coliiiiiii  H',,  the  wiinl  coni- 
lioiit'iii  would  produce  ;i  detlection  of  7/12 X1.">X sin.  4r»°=(».'J 
yjirds  riulil  :  wJucli  apiilied  to  tlie  "  o))serveil  nieiin  error  in 
detlection  "  of  •_'."!  yards,  would  uhe  the  "  true  mean  error  in 
dellei-tioH  ■■  under  sraiidard  coudilions  lo  l>c  iM — 0.2=18.8 
>ards  riirlit. 

8.  Final  results  for  this  one  gun. — 'I'lie  linal  results  for 
this  ;;iui  show  that  if  it  were  aimed  at  the  hulTs-eye  of  the 
tarjret.  as  l>efore  explained,  its  shot  would,  under  standard 
conditions,  fall  52.3  yards  beyond  (over)  and  IS.S  yards  to 
the  ritrbt  <»f  where  they  should  fall,  1.  e..  under  standard  con- 
ditions its  mean  error  in  range  is  52. B  yards  over  and  its 
mean  lateral  eiror  or  mejin  error  in  deflection  is  IS.S  yards 
ii,i:ht.  From  colinmi  18  of  range  tables,  for  lateral  motion 
of  target  perpendicular  to  line  of  tire  for  speed  of  12  knots, 
the  deviation  is  found  to  be  W  yards.  K'olunui  IS  is  used 
because  all  detlection  di-ums  are  graduated  in  knots,  consider- 
ing gun  stationary  and  target  moving  perpendicular  to  the 
line  of  fire.)  Hence,  for  a  lateral  deviation  of  18.8  yards  right 
at  7.500  yards  range  the  deflection  dr\im  .scale  should  be  cor- 
rected ]8.8Xi^  knots=3.8  knots. 

If  the  distauce  of  each  shot  from  the  mean  point  of  im- 
jiact  be  measured  and  the  mean  of  these  distances  l)e  found, 
we  have  a  quantity  called  the  "mean  disi)ersion  from  the 
mean  point  of  impa<-t.'"  This  information  is  desirable  because 
it  gives  an  idea  of  the  acciu'acy  or  consistent  shooting  of  a 
gun.  For  example,  one  gun  of  a  ))attery  may  have  its  mean 
point  of  imi»act,  with  reference  to  a  certain  target,  100  yards 
over  and  25  yards  right,  but  all  the  shots  may  fall  within  a 
very  few  yards  of  this  point  and  be  closely  grou])ed  around  it. 

Another  gun  of  the  same  battery  may  have  its  mean  point 
at  the  same  point,  i.  e.,  100  over+25  right,  but  its  shot  may 
he  so  scattered  or  dispersed  with  reference  to  the  mean  jtoint 


200 


GUNNERY  INSTRUCTIONS. 


of  iiujincl    llial    I  he  .-ivcra^ie  of  tiieii'  di.stances  Jroiu  the  mean 
IMiiiit  <if  iiiipact  is  iinicli  greater  than  that  of  tlie  first  jjjun. 

It  is  usual   to  compute  tlie  (lis]»ersioii   in   raiiLie  and   (letiec- 
•tion  separately. 

As  an  exani])Ie.  we  will  Hud  tlie  "  mean  (lis]K'rsiou  from 
Hie  mean  poini  of  impact"'  of  tlie  iiun  tired  in  llit^  "problem." 
fSee  fie-.  1.) 


No.  of  shot. 


Distance  from  mean 
point  of  impact. 


In  deflec- 
tion. 


Mean  dispersion  from  point  of  impact:  Range,  75  yards;  deflection,  7.5  yards. 
The  above  quantity  is  often  called  the  "mean  deviation  from  the  mean  point  of 
impact." 

413.  Problem  2 — To  find  possible  number  of  hits  on  tar- 
get of  a  certain  size. — The  mean  errors  (deviations)  in  range 
and  angles  of  fall  of  the  guns  of  a  certain  ship,  when  firing 
at  a  range  of  7,800  yards  were  as  follows: 


Caliber. 

Mean 

error  in 

range. 

Angle  of 
fall. 

6-inch 

Yards. 
50 
39.5 
40 

0            / 

11    08 

8-inch 

8    04 

12-inch 

.')    41 



GUNNERY  INSTRUCTIONS.  201 

l-'i-mii  ciii-li  <;ilil)ei-  1(K»  shells  iiic  tired  al  a  \  eil  icul  target 
screen  wliieli  is  MO  feet  high  and  suthciently  lonii'  lo  catc-h  alt 
shot   in  delleriioii.  ihe  screen  heini;-  T.StK)  yards  distant. 

11"  the  mean  point  of  impact  of  eaeli  caliher  is  al  the  center 
of  tli(  t<ir<i(1  xi-yvcH.  lind  the  maximum  possihle  niuuher  of 
hits  that  can  lie  made  on  this  size  screen  by  euvh  caliber. 

HoUilUni.  \\v  hrst  lind  1  ho  danger  space  of  a  30-foot  target 
lor  each  of  the  .uiveu  unns  with  their  angle  of  fall  : 

6  inches o}'=M''  08' 

S  inches w^  8°  04' 

1-^  inches w=  5°  41' 

Iteferring  t(^  Alger's  l^xterior  Ballistics  (p.  37).  two  for- 
mula' are  given  to  determine  the  danger  space: 


D=/j  cot  w  /       h  cot  u>\ 
D=/(  cot  coV  "'""    X    ) 


and     D 

where   ]>-^danger   si)ace   and    /i  =  lieight  of   target. 

Tlie   first   fornuUa   gives  1>   accurately   enough   for   present 

liurp()ses.  and  we  will  use  it. 

()'  iwfiea. 

D=  30  cot  11°  08'  log  30  =1.47712 

log  cot  11°  08'=  .70598 

D=152.44  feet.  log  D  =2.18310 

=50.81  yards. 

8  inches. 

D=30cot8°04'  log  30  =1.47712 

log  cot  8°  04'=  .84855 

D=212.67  feet.  log  D  =2. 32567 

=70.89  yards. 


202  GUNNERY  INSTRUCTIONb. 

12  inches. 

D ^30  cot  5°  41'  log  80  =1.47712 

log  cot  5°  41' =1.00209 


D=301.445  feet.  log  D  =2. 47921 

=100.48  .yards. 

Agaiu  referring  to  Alger's  Extericir  Ballistics,  Chapter  XIII. 
on  Accuracy  and  Probability  of  gunfire,  and  to  the  table  on 
page  129  in  which,  in  the  case  we  are  considering,  a  equals 
one-half  the  danger  sjtace  of  rhe  target,  and  y  eciuals  the 
mean  erroi-  in  range: 

Case  I,  6-inch  gun. 

T    ^1  •                   50.81  yards     „^  „,-        j 
In  this  case,  n  = -^ =25.25  yards. 

and  7=mean  error  in  range,  or  50  yards. 

«=2^5=.509 

7         50 

Entering  the  table  on  page  129,  referred  to  above,  we  find  the 
value  of  P  corresponding  to  this  value  of—  to  lie  betveen  3.10 

and  .368. 

By  Interpolation : 

■^^^-■^^\^09=.00522 


.1 

or  the  corresponding  value  of  P  for  .509 'is  .315.  That  is,  we 
may  expect,  under  the  given  conditions.  31.5  per  cent  of  6-inch 
hits. 


GUNNERY  INSTRUCTIONS.  203 

Case  II,  8-inch  gun. 

70.9         ,       _  ,.         , 
«=    ^— yards  =  .io.4o  yanlt^ 

7=39.5  yards. 

a     35.45      ,,^_ 
=on  tc  =^9< 
7     39.5 

P=.52G 

Tluit  is  we  iu;iy  expect.  uikUm-  the  uiveu  conditions,  52.6  per 
(•(Mit  of  8-inch  hits. 

Case  III.  12-iiich  (/tin. 

100.48     ..  _  , 

(!='  —^ — =50.24  yards 

7=40  yards 

a     50.24     ,  ^.,. 
7       40 
P=.683 

That  is,  we  may  expect,  inider  the  liiven  rojulilions.  68.3  per 
cent  of  12-incli  hits. 

414.  Problem  3. — To  find  angle  of  departure  for  an  ele- 
vated target. — .Vn  aeroplane  is  lioverin,s;  over  a  point  2.000 
.\ai-ds  distant,  in  a  liorizontal  line,  from  a  3-iuch  gun  firing  a 
15-i)ound  shell  with  an  initial  velocity  of  2,500  f.  s.  If  tlie 
altilnde  of  the  aeroplane  he  1.000  feet,  wliat  sliouhl  he  the 
angle  of  departure  to  hit  it?  .\11  conditions  are  standard 
f=l.  B  =  l. 

Snhtiion. — In  this  problem  tlie  angle  of  position  is  such  that 
ilic  priiHJple  of  •■  rigidity  of  trajectory  "  liol<ls  tnic.  Il.^nce  the 
range  on  an  inclined  plane  may  be  assumed  to  be  practically 
the  same  as  the  range  on  a  horizontal  plane,  which,  in  this 
case,  is  6,000  feet,  without  an  appreciable  diflerence  in  the 
angle  of  departure. 


204  GUNNERY  INSTRUCTIONS. 

liefci-i-inj;  t(i  AlKer'.s  Exterior  Jiallisl  ics  (p.  79),  Case  V, 
uiven  tlie  initial  velocity,  weight,  and  diiinieter  of  projectile, 
lioriscontal  and  vertical  coordinates  of  target  the  problem  is 
III  find  tlic  angle  of  departure: 

I.     V.=2,500  f.  s. 
/c=15  pounds. 
(1=3  inches. 
.r=6,000  feet. 
2/ =1,000  feet. 
Fornfulje  to  tind  a : 


X 


V 

tan  p=- 

For  getting  s,  A^,  Av,  and  use  of  Ballistic  Tables  No.  1  in 
Alger's  Exterior  Ballistics,  refer  to  Chapter  V,  Alger. 

For  discussion  of  principles  of  "rigidity  of  trajectory"  see 
pages  14  and  29,  Alger. 

a.=15      log  1.17-609 

d^=      9  log    .95424 

fr=  log    .22185 

,'S=6000  log  3.77815 

^=3600  log  3.55fi30 

Sy=3297.6 
Sz=6897.6 

Z=1582.5 

.V=1000  log  3.00000 

.T=6000  log  3.77815 

p=9°  27'  45"'  log  tan     9.22185 

V=2500 


GUNNERY  INSTRUCTIONS.  208 

2=1582.5 
A?' =  ]  38.07  'rv=  .05524 

A2=428.75 
AA=290.68  log  2.4(i34l 

^^= AS =3600  log  3.55630 

aa 

-g  =.08074  log  8.90711 

I  y=.  05524 

■^-Ii'  =  .02550  log  8.40654 

(7=  log    .22185 

2a.x=2°  25^  b^y  lug  siii     8.62739 
sin  2  «a;=. 04245 

tan /)=.  1^667  log  cos  9.99405 

.20912  log  9^32039 

2a-p=n°  M'  \A"  log  sin  9.31444 
2a =21°  2F  59'^ 
a=10°  40'  59^' 

415.  Problem  4. — To  find  range  and  deflection  for  open- 
ing fire  under  service  conditions. — Enemy's  course  NNW., 
speed  l.l  knots.  Your  course  XK..  si)eed  15  knots.  Wind  from 
east  with  velocity  of  VI  knots.  Temi)er:iture  of  powder.  75° 
v.:  all-.  50°  v.:  shell  standard,  12  inches;  barometer,  ;}(>.44: 
5=1.05. 

.\t  the  instant  you  are  (>.(><»<•  yar<ls  south  of  tlie  enemy  you 
intend  to  tire  a  trial  siiot.  How  would  you  set  yotu-  sights  in 
lauge  and  deliectionV 

Solution. 
[From    Table    II,    Alger's    Exterior    Ballistics.! 

1    5=105.    Taking  1.00  as  normal,  density 

Barometer.  30.44.  -in-       i  aa     r   .    ,. 

o         \        of   atinosiihere    is   I.O.i  —  1.00=5  per 
l^hermometer.  .>0    F.  ^    ,  , 

cent  anove  normal. 


206  GUNNERY  INSTRUCTIONS. 

Tciniicratui-t*  of  i)()W(lei"=7")°  V.  Xoniial  teiiiperature  of 
IKPwdcr  is  90°  F.  Therefiu'c.  iliis  jMiwiler  is  90  —  75=15°  be- 
low normal. 


/  "^ 


><■ 


Resolving  force.s  ±  and  1 1  to  plane  of  fire  we  have: 
.'^peed  of  ship  li  to  plane  of  fire=15  cos  45  =10.61  knots. 
Speed  of  ship  ±  to  plane  of  fire=15  sin  45  =10.61  knots. 
Speed  of  target  1 1  to  plane  of  fire=15  cos  22^=13.86  knots. 
Speed  of  target  ±  to  plane  of  fire=15  sin  22^=  5.74  knots. 
Speed  of  wind  ±  to  plane  of  fire=  12.00  knots. 

From  12-inch  Range  Tables,  range  H.OOO  yards: 

(a)  Column  14.     Change  of  range  for  motion  of  gun  in  plane  of 
fire,  speed  12  knots=37  yards. 

.-.  Change  for  10.61  knot8=^^^^^ig^^=32.71. 

(b)  Column  17.  Deviation  for  lateral  motion  of  gun  ±  to  plane 
of  fire,  speed  12  knots=42  yards. 

.'.  Deviation  for  10.61  knot8= — '-j^ — ^=37.14. 

(c)  Column  15.  Change  of  I'ange  for  motion  of  target  in  i>lane  of 
fire,  speed  12  knots=47  yards. 

iQ  »fiv47 
.-.  Change  for  13.86  knots=^^^^^  =54.29  yards. 


GUNNERY  INSTRUCTIONS. 


207 


(d)  Column  IS  deviation  for  hiterul  motion  of  target  J.  to  plane 

of  fire,  speed  12  knot8=47  yards. 

5  74X47 
.•.   Deviation  for  5.74  knot8=  "   ,.-, —  =22.48  yards. 

{(')  Column  ill.  Deviation  for  lateral  wind  component  of  12  knots 
=5  yards. 

(/)  Column  12.  Ohaiige  of  range  for  variation  of  density  of  air 
of  ±  10  per  cent =83  yards. 

.•.  (hauge  tor  o  per  cent  =  -  i^-  =41.0  yards. 

(g)  From  "'Explanatory  notes"  in  front  of  Range  Tables  a  change 
in  temperature  of  powder  of  10°  F.  causes  a  variation  in  muzzle 
velocity  of  35  f.  s. 

.•.  Variation  of  muzzle  velocity  for  15°  F.=52.5  f.  s. 

Column  10.  Change  of  range  for  variation  of  muzzle  velocity  of 
±50  f.  s.=175  yards. 

.".  Change  for  52.5  f.  s.  =  — '-^ =183.75. 

oO 

These  I'esults  are  tabulated  as  follows: 

12-inch,  6,000  yards. 


Argu- 
ment. 

Over. 
32.7 

Short. 

Right. 

Left. 

t'luiiigi'  of  rangi'  for  iiiolion  of  fun  in  plane 
of  fire 

10.  til 

10.61 

13.86 

.^.74 
12 

-t-  5 
-15 

Deviation  for  lateral  motion  of  gnnltoplane 
of  fire .... 

37.1 

Change  of  range  for  motion  of  target  in  plane 
of  fire 

54.3 

Deviation  for  lateral  motion  of  target  X  to 

plane  of  fire . . 

22.5 

De  vial  ion  for  lateral  wind  component 

Change  of  range  for  variation  in  density  of 
iiir per  cent. . 

Change  of  range  for  variation  in  tempera- 
ture of  powder degrees. . 

5.0 

41.5 

183.8 

^— -uit ^i^rS'-: 

1 

32.7 

279.6 
32.7 

59.6 
5.0 

5.0 

1 

246.9 

54.6 

208 


GUNNERY  INSTRUCTIONS. 


.-.  Sight  bar  should  be  set  6,000+246.9=6,246.9  yards. 

.VcTuiillv    the  setting  would  V)e  6,250  yards. 

The  (U'tiectiou  scales  being  graduated  for  "knots  speed  of 
target."  .")4.6  yards  must  be  converted  to  knots  speed  of  target. 

Column  18.  Deviation  for  motion  of  target  J-  to  line  of  fire, 
speed  12  knots=*47  yards. 


liorfh     •         ^V^ 


y^ineJ  l2Hhoh 


eooo  ^ds 


12 
.-.1  yard=T^  knots. 

^4  fivT' 
.-.  54.6  yards=     '^^    "=13.94  knots. 

The  graduation  50,  being  zero  deflection,  to  compensate  for 
54.()  yards,  the  drum  must  he  set  at  50—13.94=36.06. 


GUNNERY  INSTRUCTIONS.  209 

A<'tu!illy,  the  settiii.u'  wmild  he  'M'>. 

416.  Problem  5. — To  find  range  and  deflection  for  open- 
ing fire  under  service  conditions. — Plot  this  situation  before 
Wfirkiii^'  tlR'  problem. 

Vdu  are  chief  fire-control  olhcer  of  a  hattle.ship  carryln.y  12- 
iiich  and  (i-iiich  .^uiis,  and  have  been  ordered  by  the  cai)taiii 
1(1  (>iien  tire  with  the  12-inch  the  instant  the  range  is  ',).<)0() 
yards,  heai-iiii;'  north. 

'I'he  speeds  and  courses  of  the  enemy  and  yourself  at  the 
in.stant  of  firiiiii  are  as  follows:  Eiiciiuj,  course  4.j°.  speed  12 
knots:  ///■/////  xliii).  course  300°.  speed  1.5  knots,  and  this  in- 
formation is  known  to  you  sutticientlx  in  advance  to  allow  fo; 
variation  from  standai-d  conditions  in  setting  your  sights.  If 
the  bai-ometer  is  29  inches,  thermometer  75°  F..  temperature 
of  the  powder  95°.  and  the  wind,  from  the  west,  is  blowing 
12  knots  over  the  surface  of  the  water,  what  would  be  the  ~ 
range  at  which  you  would  set  the  12-inch  sight  bars  for  the 
opening  sholV 

If  the  deflection  scales  of  your  guns  are  graduated  for  the 
speed  of  the  target  in  knots,  and  the  middle  line  of  zero  de- 
tlections  is  marked  50,  bow  would  you  set  the  6-inch  and  12- 
incb  detlectioii  scales  for  opening  bre  in  the  i)roblem  above? 

Sohttioii. 

[From  Table  II,  Alger's  Exterior  Ballistics.] 

Taking  1.00  as  normal  density  of 


Barometer  29.00 
Thermometer  75°  F 


5  =  .9o' 


atmosphere,  1.00— .95=5  percent  be- 
low normal . 

Temperaiure  of  powder  95°  F.     Normal  temperature  of  powder 
is  90°  F.     Therefore  this  powder  is  95°-90°=5°  above  normal. 
Resolving  forces  1 1  and  J.  to  plane  of  fire  we  have: 
Speed  of  ship  1 1  to  plane  of  fire=15  cos  60=7.5  knots. 
Speed  of  ship  ±  to  plane  of  fire=15  sin  60=12.99  knots. 
Speed  of  target  1 1  to  plane  of  fire=12  cos  45=8.49  knots. 
.34776—18 14 


210  GUNNERY  INSTRUCTIONS. 

Speed  of  target  1.  to  plane  of  fire=12  sin  45=8.49  knots. 
From  12-in('h  range  tables  for  range  of  9,000  yards; 
(a)  Column  14.  Change  of  range  for  motion  of  gun  in  plane  of 
fire  for  speed  of  12  knots=52  yards: 

.".  Change  for  7.o  knots=— yp — =32.5  yards. 

{b)  Column  17.  Deviation  for  lateral  motion  of  gun  I  to  line  of 
fire  speed  12  knots=63  yards. 

19  9QV63 
.-.  Deviation  for  12.99  knots=^^^y^  =68.198  yards. 

(c)  Column  15.  Change  of  range  for  motion  of  target  in  plane  of 
fire  speed  12  knots=74  yards. 

•   .•.  Change  for  8.49  knots=  '  '    ^ —  =52.355  yards. 

(d)  Column  18.  Deviation  for  lateral  motion  of  target  ±  to  line 
of  fire  speed  12  knots=74. 

.■.  Deviation  for  8.49  knots='  "   ,,-, —  =52.355  yards. 

(r)  Column  16.  Deviation  for  lateral  wind  component  of  12 
knots  1  to  plane  of  fire  =  ll  yards. 

(/)  Column  12.  Change  of  range  for  ±  10  per  cent  variation  in 
density  of  air=174  yards. 

.'.  Change  for  5  per  cent  variation  =     ^     =87  yards. 

(g)  From  explanatory  notes  in  front  of  range  tables  a  change  in 
temperature  of  powder  of  10°  F.  causes  a  change  in  muzzle  velocity 
of  35  f.  s. 

.■.  Change  for  5°  =  — ,-^^-^  =  17.5  f.  s. 

Column  10.  Change  of  range  for   ±  50  f.  s.  change  in  muzzle 

velocity=2.54  yards. 

17  5V254 
.-.  Change  for  17.5  f.  s.  =  — ^^^^ =88.9  yards. 

These  results  are  tabulated  as  follows: 


GUNNERY  INSTRUCTIONS. 


211 


Argu- 
ment. 

Over. 

Short. 

Right. 

I^fl. 

Clmntio  ol  range  for  motion  of  gim  in  plane 
of  lire     ... 

7.5 

12.99 

8.49 

8.49 
12.0 

+  5 
+  5 

32.5 

Dcvialidii  for  lateral  motion  of   gim  1  to 
plane  of  /ire 



68. 2 

Change  ol  niiige  for  motion  of  target  in  plane 
of  fire 

52.4 

Deviatidii  for  lateral  motion  of  target   1  to 
plane  of  five. . .          

52.4 

1  )eviat  ioti  for  lateral  wind  component 

11. 0 

Change  of  range  for  variation  of  density  of 
air per  cent . . 

87.0 

88.  9 

Change  of  range  for  variation  in  temperature 
of  powder degrees. . 

I--,  1  ..      n                            /I5(i  yards  over.. . 

208.4 
52.4 

52.4 

11.0 

120. 6 

'•'"'^''^■^"'^ {l09.6  yards  left.. 

11.  J 

156.0 

109. 6 

.-.  Sight  bar  should  be  set  at  9,000-156=8,844.  Actually  it 
would  be  set  at  S.S.IO  yartls. 

The  detlectioii  scales  of  all  yuus  are  ^iraduated  for  "knots 
s[)eed  of  target,"  therefore  the  l()9.G  yards  must  be  converted 
to  knots  speed  of  tarjjet. 

Column  18.  Deviation  for  motion  of  target  ±  to  plane  of  fire 
speed  12  knots=74  yards. 

.■.  i  yard=12/74  knots  on  drum. 

ion«        A      109.6X12     ,_^,      ^  , 

.  .  109.6  yard8= ^7 —  =1/.//  knots  on  drum. 

'I'lie  uraduation  .">()  being  zero  deflection  to  compensate  for 
10!). G  yards  left  we  should  set  drinn  at  .")0+]7.77=(!7.77.  Ac- 
tually it  would  be  set  at  68.0. 

For  the  6-inch  guns  the  method  is  tlie  same,  using  the  (i-inch 
range  tables  for  O.OOO  yards. 

From  colunuis  1(5,  17,  and  18  we  find  that  due  to  wind. 
speed  of  ship,  and  speed  of  target  X  to  plane  of  fire  the  shell 
would  1h'  displaced  118.03  yards  to  the  left  of  target.  (In 
this  case  we  are  not  concerned  with  the  error  in  range.) 


212 


GUNNERY  INSTRUCTIONS. 


!  Argu- 
ment. 


Deviation  for  lateral  motion  of  gun  J.  to  plane  of  flre 

Deviation  for  lateral  motion  of  target  J.  t  o  plane  of  fire  . 
Deviation  for  laleral  wind  component 


12.99 
8.49 

12.00 


Right.     Left. 


31.0 


31.0 


76.86 
72.17 


149. 03 
31.00 

118.03 


From   ('oiiuiiii   IS  tlu'  deviation   for  12  knots  speed  of  tar- 
get=102  .vard.><. 

118x12 


For  118  yards  it  would  be 


102 


=13.88. 


.•.  Deflection  scale  should  be  set  at  50+13. 88=();i. 88.  Actually 
it  would  be  set  at  64. 

417.  Problem  6. — (1)  To  find  change  in  sight-bar  range 
when  shot  does  not  hit  bull's-eye;  (2)  to  find  fall  of  shot 
when  sights  are  not  corrected  for  wind  and  speed. — Using 
tile  12-in(li  range  table,  determine  tlie  following: 

(1)  .\  iiun  is  fired  at  a  vertical  tarj^et  screen  2,0(M»  yards 
('isiant  with  si,iihts  set  for  a  range  of  2,000  yards.  The  shell 
I'iei-ced  the  target  6  feet  ahove  the  buirs-eye.  Wliat  siglit-bar 
range  nmsi  l)e  used  if  the  next  sliot  is  to  hit  tlie  bull's-eye? 

(2)  At  a  certain  instant  a  ship,  steaming  at  lo  knots  on  a 
northeast  course,  is  directly  south  of  a  stationary  target 
which  is  8,000  yards  away.  An  18-knot  breeze  is  blowing  from 
west-southwest  at  the  time.  Find  the  changes  in  range  and 
(Ic/lcctioii  due  to  (1)  speed  of  ship  and  (2)  wind;  and  state 
wliere  the  shot  would  fiill  if  the  ship  fires,  at  the  instant  noted 
above,  with  the  sights  set  for  8,000  yards  and  no  deflection. 

Solution. —  ( 1 )    F"'roni  1 2-inch  range  tables,  range  2.000  yards : 
Colunui   19.  Chaufici   in   height   of   imiiact   for   variation   of 
±100  yards  In  sight  bar=4  feet. 


GUNNERY  INSTRUCTIONS.  213 

Change  for  6  feet  height  of  impact=150  yards. 
Set  sight  bar  at  2000-150  =  1.850  yards. 


,1<'^' 


:Jrip 

(2)   Ke.sdlviiijj;  forces  -L  iiiid  II  to  plane  of  fire. 

Speed  of  siiip  II  to  plane  of  tire  =15  cos  45=10.61  Ivuots. 

Speed  of  ship  -L  to  plane  of  fire  =15  sin  45=10.01  Imots. 

Speed  of  wind  II  to  jdane  of  fire  =18  cos  67A=()..S!t  knots. 

Speed  of  wind  -L  to  plane  of  fire  =18  sin  67^=16.03  knots. 
From  12-incli  range  tables,  range  8,000  yards: 
(a)  Oohunn  14.     Change  of  range  for  motion  of  gun  in 

1)1  ane  of  fire,  speed  12  knot.s=47  yards. 

.  ,      .      10.61X47      .,  .„         , 
.-.  Change  for  1(1. (Jl  knots= j^^^— =41.56  yards. 

{b)   Colnnm   17.     Deviation   for  lateral   motion   of  gun    -L 
to  plane  of  fire,  speed  12  knots=56  yards. 

.-.  Devi:)ti(.n  for  10.61  =  -  ■y;^"=49. 51  yards. 

{c)    Coiniiin    i:;.     (Mianiiv  of  range  for  wind   comi)onont   in 
plane  of  fire,  speed  12  knots=17  yards. 

6.89X17     „... 
.-.  Change  for  6.89  knot?= — ^ — =9./()  yards. 


214 


GUNNERY  INSTRUCTIONS. 


(d)   Coluum  16.     Deviation  for  lateral  wind  comitonent  of 
12  knots=8  yards. 

.".  Deviation  for  16.63  knot8= — -rr^ — =11.09  yards. 
These  results  are  tabulated  as  follows : 


' 

Argu- 
ment. 

Over. 

Right. 

Change  of  range  for  motion  of  gun  in  plane  of  Are 

Deviation  for  lateral  motion  of  gun  x  to  plane  of  fire 

Change  of  range  for  wind  component  in  plane  of  fire 

Deviation  for  lateral  wind  component 

10.61 

10.61 

6.89 

16.63 

41.  56 
'9.'76' 

'  49.' .51 
ii.69 

51.32 

60.60 

( <i )   Effect  due  to  movement  of  ship :  41.56  over,  49.51  right. 

(  h )    Effect  due  to  wind :  9.76  over,  11.09  right. 

ComI)ining  (a)  and  (b)  we  find  the  shell  would  fall:  41.56+ 
9.76=51.32  yards  over.  49.514-11.09=60.60  yards  right. 

418.  Problem  7. — To  find  size  of  target  to  catch  all 
properly  aimed  shots. 

If  the  mean  error  in  range  of  a  pointer's  gun  be  25  yards. 
;it  a  range  of  1.700  yards,  what  should  be  the  height  of  a 
vertical  target  screen  to  catch  all  ]iro[)erly  aimed  shots,  the 
point  of  aim  being  the  center  of  the  target,  the  angle  of  fall 
being  1°  23' V 

Definition  of  terms: 
P=Probability  of  hitting. 

a//=One-half  height  of  target. 


vard;- 


feet. 


7./'^Mean  deviation   in  range= 

7.(/^i\Iean   vertical   deviation. 
a,=Angle  of  fall=l°  23'. 

From  Alger's  Exterior  Ballistics,  page  129,  probability 
table,  if  the  probability  of  hitting  (P)  is  100  (.999),  the  dis- 
tance ay  must  equal  four  times  the  mean  vertical  deviation,  7//. 


GUNNERY  INSTRUCTIONS. 

iiiiii  Ali:cr"s  lOxtcriitr  JJallisiics.  \tn'j:ti  13S),  art.  HtJ: 

yr=ig  cot  u'. 
SdlviiiK : 

7a: =75'         loo     1.875U() 

co  =  l°  2.r  tan     8.38289 


7(/  =  l'.81     loo     10.25795 


ay 


r.ul  -^  must  equal  4. 

yy  ^ 

.-.  m/=4X72/=4X1^81  =  7'.24. 

.-.  Height  of  target  (2fl?/)=14.4S  feet. 


216 


XoTK. — It  will  also  be  noted  that  4Xf/.;/,  or  4XTr>'=30U',  is 
e(iual  ti)  half  the  danger  space. 

419.  Problem  8. — To  find  change  in  range  due  to  varia- 
tion from  standard  (1)  temperature  of  powder,  (2)  initial 
velocity,  (3)  weight,  (4)  density  of  air. — Using  the  12-ineh 
range  tal)k'.  determine  the  following: 

(1)  What  would  be  the  change  of  initial  or  nuizzle  velocity 
if  the  tenii)eratur(>  of  the  charge  were  101°  F.  in.stead  of  90° 
v..  for  wliicli  the  range  t:ibles  were  caleulated V 

(2)  What  will  be  the  chanue  of  range  due  to  this  change 
in  nniz/.le  velocity  if  the  angle  of  dopartm-e  be  3°  12' V 

(3)  If  the  gun  is  fired  at  this  elevation  (3°  12').  standard 
eondition.   except   that   the  shell   weighed  S2()  pounds   instead 


216  GUNNERY  INSTRUCTIONS. 

of  870  i)()im(ls.  liow  imicli  will  the  ranjie  be  increased  or  de- 
creased ? 

(4)  All  conditions  being  standard  except  the  density  of  the 
air,  which  is  5  per  cent  greater  than  normal,  what  will  be  the 
range  of  the  shell  if  it  is  fired  with  an  angle  of  departure 
of  3°  41'.9? 

t^oliition. —  (1)  The  teniperatnre  of  the  charge  is  101°  — 
l)(l°  =  ll°  above  normal. 

From  explanatory  notes  in  front  of  range  tables  we  find 
that  a  change  of  10°  F.  in  temperatnre  of  powder  changes 
the  initial  velocity  35  f.  s. 

.'.  11°  above  normal  increases  the  initial  velocity  by  38.5  f.  s. 

(2)  From  columns  1  and  2  an  angle  of  departure  of  3° 
J 2'  gives  a  range  of  8.000  yards  with  normal  initial  velocity. 

To  find  change  due  to  initial  velocity,  increased  as  in  (1)  — 
that  is,  by  38..J  f.  s. — proceed  as  follows: 

Column  10.  Change  of  range  for  variation  of  ±50  f.  s.  initial 
velocity=229  yards. 

.-.  Change  for  38.5  f.  s. =^^^^^=176.33  yards. 

(3)  Notp:. — Charge  remaining  the  same,  weight  of  .shell  in- 
creased, will  it  go  farther  or  less  with  the  same  angle  of 
(ieparture?  The  following  net  result  was  determined  from 
pi-oving-ground  data  : 

For  each  case  the  initial  velocity  is  reduced  with  heavier 
sliell  and  the  range  for  short  ranges  is  decreased  and  foi 
long  ranges  is  increased. 

Column  11.  Variation  for  ±10  pounds  in  weight  of  projectile= 
39  yards. 

.•.  Variations  for  (870— 820)  50  pounds=195  yards  increase  in 
range. 

(4)  From  colnnms  J  and  2  an  angle  of  departure  of  3° 
IT.O  gives  a  r;inge  of  9,000  yards  under  standard  conditions. 

Column  12.  Change  of  range  for  variation  of  density  of  air 
of  ±10  per  cent=174  yards. 


GUNNERY  INSTRUCTIONS. 


217 


5X174 
.-.  Change  for  5  per  cent=--^Q— =87  yards  decrease. 

Tlierefc.re  actual   raiij;e=9.000— 87=8,913  yards. 

420.  Problem  9. — To  find  range  and  deflection  for  open- 
ing fire  under  service  conditions. — ]>ra\v  a  diagram  of  the 
si1uati<Mi  before  solving. 


Speed . . 
Course. 


Firing  ship. 


18  knots. .. 
Northeast. 


Target  ship. 


15  knots. 
East  northeast. 


Wind  from  the  northwest,  blowing  15  knots  per  hour  over 
the  water. 

Barometer,  30.02".  Temperature  of  air,  78°  F.  Tempera- 
ture of  powder,  83°  P. 

( 1 )  AYhat  should  be  the  readings  of  the  range  and  deflection 
scales  for  opening  flre  with  the  12-inch  guns  at  the  instant  the 
enemy  hears  N.  30°I<:.  and  is  distant  8.tKK)  yardsV 

(2)  What  should  be  the  reading  of  the  6-inch  deflection 
scales  at  this  moment  if  fire  is  opened  with  the  6-inch  also? 

Solution. 
[I-'rom  Table  II,  Alger's  Exterior  Ballistics.  1 

6  =  .978.  Taking  1.00  as  normal,  density  of 
atmosphere  =  1.00  -  .978  =  2.2  per  cent 
below  normal. 

Temperature  of  powder,  83°  F. ;  normal  temperature  powder 
is  90°  F. ;  therefore  this  powder  is  90  —  83  =  7°  below  nor- 
mal. 

Resolving  forces  //  and  ±  to  plane  of  fire.  (Traverse  tables 
niciif  he  used)  : 

Speed  of  ship  /    to  i)lane  of  fire  =  18  cos  15°  =17.38  knots. 
Speed  of  ship  ±  to  plane  of  fire  =  18  sin  15°  =  4.66  knots. 
Speed  of  target  //  to  plane  of  fire  =  15  cos  37 A  °  =  11.90  knqts. 
Speed  of  target  ±  to  plane  of  fire  =  15  sin  37*°  =  9.13  knots. 


Barometer  30.02 
Thermometer  78°  F. 


218 


GUNNERY  INSTRUCTIONS. 


Speed  of  wiucl  //  to  plane  of  tire  =  15  cos  75°  =  3.88  knots. 

Speed  of  wind  ±  t(j  plane  of  tire  =  15  sin  75°  =  14.49  knots. 
( 1 )   P^rom  12-inch  range  tables  for  range  of  8,000  yards : 
{a)   Column   14.     Change   of  range   for  motion   of  gun    in 

plane  of  tire,  speed  12  knots  =  47  yards. 

17  '^ftV47 
.-.  Change  for  17.38  knots^^-     °^^     =68.07  yards. 

(h)   Column  17.     Deviation  for  latei-al  motion  of  gun  ±  to 
line  of  tire.  si)eed  12  knots  =  56  yards. 

.■.  Deviation  for  4.()6  knots  =       -.^ — =21.75  yards. 


{(■)    Colunni   15.     Change  of  ran.uv  for  motion  of  target  in 

lihine  of  tire,  speed  12  knots=65  yards. 

11  QOVfi^ 
.-.  Change  for  11.90  knot8=^5^^^^^=64.46  yards. 

('/)   Column  18.     Deviation  for  lateral   morion  of  target  ± 
to  line  of  fire,  speed  12  knots=05  yards. 

9  13X65 
Therefore  deviation  for  9.13  knots=-^-Y^ — =49.45  yards. 

(e)   Colunui   13.     Change  of  range  for   wind  component   in 
plane  of  tire,  speed  12  knots=l7  yards. 


GUNNERY  INSTRUCTIONS. 


219 


=  29.92  yards. 


.-.  Change  lor  3.88  knot,s=-^^2 — =^-^^  y^i"^*^- 
(/)   Column    ](>.      Dovintion    lor    l:it(>r:il     wiiitl    i-Dinpoiieiit, 
siteoil  12  kn()ts=8  yards. 

.-.  Deviation  for  14.49  knot8=-^^j2 — ""^-^^  y-Auis. 
{(/)   Coliiiim  12.     (Miiiujie  of  range  for  variation  of  density 
of  air  of  +  or  —  Kl  iter  (•ent=136  yards. 

2  2X136 
.-.  Change  for  2.2  per  cent=  -^^ —  = 

( /( )  From  explanatory  notes  in  front  of  range  tables  a 
change  in  temperature  of  powder  of  l(t°  F.  causes  a  change  in 
mu;'-zle  velocity  of  35  f.  s. 

.-.  Change  for  7°  = '-^=24.5  f.  .s. 

Cohnmi    10.      Change   <tf   i-ange   for    variation    of   ±50   f.   s. 

initial  velocity  —  229  yards. 

"^4  5  X  229 
.-.  Cliange  for  24.5  f.  8.  =  ^^^^^ —  =  112.21  yards. 

These  results  are  tabulated  as  follows: 


Change  of  range  for  motion  of  gim  in  plane 
of  firo 

Deviation  for  lateral  motion  of  gun  1  to 
plane  of  fire 

Change  of  range  for  motion  of  target  in  plane 
of  fire 

Deviation  for  lateral  motion  of  target  1  to 
plane  of  fire 

Change  of  range  for  wind  component  in 
plane  of  fire 

Deviation  for  wind  component  1  to  plane 
of  fire 

Change  of  range  for  variation  in  density  of 
air 

Change  of  range  for  variation  in  tempera- 
ture of  powder 


Argu- 
ment. 


Over.    Short.    Right. 


Final  results:  S4.1S    yards   short,    18.04 
yards  left 


17.38 
4.6tj 

11.90 
9.13 

3.88 
14.49 

+  2.2% 


68.07 


29.92 


Left. 


21.75 


64.46 


5.. 50 


112. 21 


9.60 


49. 4.T 


97.99 


182. 17 
97.99 


31.41 


84.18 


49.45 
31.41 


18.04 


220 


GUNNERY  INSTRUCTIONS. 


Tliereloiv  siiiiit  bar  should  l)e  set  at  S,0<J()  +  84.1,S=8,084.1S 
.vards.    Actually  it  vvoukl  be  set  at  8,100  yards. 

The  deflection  scales  of  all  gnus  are  graduated  in  "  knots 
speed  of  target,"  tlierefore  the  18.04  yards  must  be  converted 
to  knots  speed  of  target. 

Column  18.  Deviation  for  lateral  motion  of  target  1  to  line 
of  tire,  speed  12  knots=65  yards. 


12 
1  yard=KK  knots  on  drum. 


.-.18.04  yards = 


12X18.04 

r>5 


=  3.33  knots. 


a^herefore  the  deflection  drum  sliould  be  set  at  50+3.33=53.33. 
Actually  it  would  l)e  set  at  53. 

(2)  For  the  6-inch  deflection  the  method  is  the  same,  using 
the  6-inch  range  tables  for  8,000  yards. 

From  columns  16,  17,  and  18  we  find  that  due  to  wind,  speed 
of  ship,  and  speed  of  target  1  to  plane  of  fire  the  shell  would 
be  displaced  12.75  yards  to  left  of  the  target.  (In  this  case 
we  are  not  concerned  with  the  error  in  range. ) 


Argu- 
ment. 

Right. 

Left. 

Deviation  for  lateral  motion  of  gun  1  to  plane  of  fire 

Deviation  for  lateral  motion  of  target  1  to  plane  of  fire. . . 
Deviation  for  lateral  wind  component 

4.66 

9.13 

14.49 

24.46 
"28.' 98' 

"66.' ig 

53.44 

66.19 
53.44 

12.75 

Column  18.  Deviation  for  lateral  motion  of  target  1  to  plane 
of  fire,  speed  12  knots=87  yards. 

..1  yard  =  ny  knots. 

.".  12.75  yards  = ^~ — =1.76  knots. 

0/ 

Therefore  the  deflection  drum  should  be  set  at  .50-(-1.76= 
51.76.     Actually  it  would  be  set  at  52. 


CHAPTEK  18. 
STATION  BILLS. 

421.  Scope  of  chapter. — The  followiiii:  is  a  hriol'  outiiiir  of 
ii.  lire-coutrol  bill  for  an  all-big-guii  ship.  Numerous  varia- 
tions of  the  plan  herein  outlined  will  !)e  found,  and  it  is  not 
at  all  correct  in  detail  for  all  shij)s.  The  method  of  using 
tlie  system  of  communications  varies.  Some  vessels  use 
clocks  in  subcentral.  vi^hile  others  rely  on  curves  for  tracking 
the  enemy,  or  for  graphically  keeping  the  range  and  change 
of  range.  The  general  plan  of  tire  control  in  all.  however,  is 
the  same. 

422.  Station  bill  and  lookouts. — In  drawing  up  the  sta- 
tion bills  particularly  for  torpedo  defense,  proper  regard  for 
conditions  of  sei'vice  should  be  observed.  Othcers  and  men 
must  be  given  stations  that  they  could  occupy  and  an  ar- 
rangement of  reliefs  nuist  be  provided  as  would  be  the  case 
in  war  when  an  engagement  might  be  inuninent. 


( il )   l'il( 

-roiilrol- 

— Firc-cdiilrol    ioifcr  jh'oiii). 

Person- 
nel. 

l>uty. 

Designation. 

Collective  fli-e. 

Group  fire. 

(^hief  fire  control,  J .  A . 
phone. 

Fire  -  control      lower 
spotter,  J.  C.  phone. 

J   D.  control         

Officer. . 

...do 

Man 

...do 

Oflicer. . 

Chief  ftrc-control  offi- 
cer talks  to  flrc-con- 
trol  switchboard. 

Kelief  spotter  ring 
salvo  signals. 

Talker  to  turrets 

Talker  to  range  Imdcrs 

and  timekeepers. 
Fires  torpedoes 

Chief  fire-control  olliocr 
spot  one  group  if  nec- 
essary. 

Spot  cither  group  as 
needed  and  ring  salvo 
signals. 

1)0. 

J.  W^.  control 

Torpedo  director 

Do. 
Do. 

221 


222 


GUNNERY  INSTRUCTIONS. 

(b)   iSuhcoitral  yrouij. 


Designation. 


Subcentral . . 
Rate  plotter. 

Clock 


Dials. 


Check  clock . 
Check  dials. . 


Tracker 

Tracker  assistant 

Timekeeper 


Tube  man 

Switchboard 

Fire-control  repairs. 


Duty. 


Person- 
nel. 


Collective  Are. 


Group  fire. 


Officer. .    Charge  of  subcentral, 

'      on  J.  A.  phone. 
...do Plot  range-finder  ob- 
servation on  rate  of 
change  board. 
Man Operate  main  clock. . . 

...do I  Operate  main  dials — 


.do. 
.do. 


Officer. 
..do.... 

Man 


.do. 
.do. 


Electri- 
cian. 


Operate  check  clock. . . 
Operate  check  dials. . . 

Tracking  board 

Assist  at  tracking 
board. 

Mark  time  for  range 
finders:  repeat  and 
record  ranges  and 
bearings;  phone  to 
range  finders. 

Repeat  voice  -tube 
communications. 

O  perate  fire-control 
phone  switchboard. 

Oyro  compass  and  re- 
pairs. 


Charge  of  subcentral. 
Same  as  collective  fire. 


Operate  clock  for  after 
group. 

Operate  dials  for  after 
group. 

Operate  clock  for  for- 
ward group. 

Operate  dials  for  for- 
ward group. 

Track  for  after  group. 

Track  for  forward 
group. 

Same  as  collective  fire. 


Do. 
Do. 
Do. 


GUNNERY  INSTRUCTIONS. 

(c)   tiaOyrouiJ. 


223 


1  )osiKnat  ion 


Dulv. 


In  charge |  In  charge. 


Telephone  range  and 
deflection  to  turrets; 
operate  deflection 
1r;insmitter. 

Operate  range  tran.s- 
raitter;  stand  by 
voice  tubes. 


'telephone  range  and 
deflection  to  after 
group;  operate  range 
and  deflection  trans- 
mitter to  after  group. 

Operate  range  and  de- 
flection transmitter 
to  forward  group; 
telephone  range  and 
deflection  to  forward 
group. 


( (I )    l'(ir(-t(>ii  (iniKp. 


Dosigiialion. 


Fore-lop  spotter. 
Fore-lop  talker.. 
Bearings 


Person- 
nel. 


Duty. 


Collective  fire. 


Group  fire. 


Officer . .    Spot  all  tuiret s Spot  forward  group. 

Man.  .  ..    Tube  to  subcentral I  Same  as  collective  fire. 

. .  .do.  .  . .!  Bearing  indicator '  Indicates    l)earing    for 

'  forward  group. 


(e)   Main-toi)  group. 


Designation. 

Duty. 
Person- 

nel.     ] 

Collective  fire. 

Group  fire. 

Main-top  spotter 

Main-top  talker 

1 

Officer . .    First-relief  spotter 

Man Tube  to  subcentral  — 

1 

Spot  after  group. 
Same  as  collective  fire. 

224  GUNNERY  INSTRUCTIONS. 

(/)    Torpiilo-ciml rol  f/roiiji. 
Designation.  I  tut  v. 

Torpedo  (.flicer Torpedo  romn. 

Torpedo  director  officer At  toritedo  director. 

(//)    Hiniav-liixlcr  (/roup. 

Each  crew  c(»iisists  of  an  otHcer  and  man   (or  two  men). 

Foi-  collective  tin  any  one  or  all  may  he  designated  to 
i-ange. 

For  f,a'oup  fire  the  system  is  Mexiblc.  and  any  twd  may  he 
designated,  each  for  one  .lirou]).  ronmuuiicate  hy  iihone  or 
\(iice  tube  to  the  tire-control  tower  and  suhccntral. 

(//)    Turret  (jroui). 

In  case  the  fore-top  spotter,  the  main-toi»  spotter,  and  the 
fire-conti-ol-tower  spottei-  are  disabled,  but  ship  is  still  able 
to  tiglit  all  guns : 

For  collective  tire  the  turret  officer  of  the  liighest  tunvt 
spots  from  his  turret. 

For  groui»  fire  the  turret  otHcer  of  the  highest  turret  iu 
each  groui>  spots  for  tluit  group. 

423.  Operation  of  system. — On  apiiroaching  the  target  the 
taking  of  ranges  and  bearings  is  conunenced  on  order  from 
the  tire-control  station.  At  tlie  order  "mark"  stop  watches 
are  started  by  men  at  each  range  finder,  at  the  station  where 
the  bearing  of  the  target  is  obtained,  on  the  line  of  communi- 
cation in  the  subcentral.  and  in  the  tire  control  station.  The 
numbei-  of  timekeepers  is  less  than  thos(»  enumerated  above 
in  .some  <'a.ses.  With  proper  means  of  connnunication  to  sta- 
tions numerous  variations  in  details  are  found.  Loss  of  one 
means  of  communication  does  not  entail  the  loss  of  the 
services  of  any  station,  but  necessitates  the  shifting  to  the 
best   auxiliary    method    of    connnunication.      At     evei'v     half 


aUNNEEY  INSTRUCTIONS.  226 

minute,  if  pussible,  a  rauge-liuder  reudiug  is  obtained.  One 
range  liuder,  tlie  best,  is  used,  tlie  otliers  standing  by.  or  the 
mean  of  readings  of  all  instruments  is  taken.  Bearings  of 
the  target  are  taken  every  half  minute,  if  a  bearing  indicator, 
wliic-li  constantly  indicates  the  bearing  of  the  target,  is  not 
installed.  These  bearings  are  relative  to  the  ship,  and  in 
degrees  from  0°  ahead  around  to  360°.  Information  regarding 
the  range  and  bearing  of  the  target  is  sent  to  the  plotting 
board,  and  plotting  to  obtain  rate  of  change  of  range  and 
course  and  speed  of  the  enemy  is  begun.  The  range  clocks 
are  located  near  the  range  dials,  so  that  the  dial  operators 
may  watch  the  clocks.  The  clocks  are  rated  for  the  proper 
rate  of  change  of  range  as  soon  as  a  rate  is  determined.  If 
all  guns  are  l)oiiig  used  on  the  same  target,  all  dials  are  set 
simultaneously  with  the  master  clock  when  the  clock  operator 
calls  out  the  range  and  only  one  range  clock  is  used,  the 
other  being  a  stand-by. 

The  man  at  the  deflection  board,  taking  the  approximate 
rate  at  which  the  enemy  is  approaching,  referred  to  a  course 
parallel  to  the  ship's  course,  and  using  bearing  of  the  enemy  as 
the  other  factor,  automatically  obtains  the  necessary  deflec- 
tion. 

The  ranges  are  sent  to  subs  by  the  range  dials  and  from 
the  subs  are  sent  out  by  visuals,  telephone  and  voice  tubes 
giving  the  information  several  seconds  later. 

The  chief  fire-control  officer  designates  the  turret  to  ftre 
ranging  shots,  and  at  the  order  to  begin  ranging  "fire"  is  dis- 
played on  all  visuals.  The  turret  designated  to  fire  ranging 
shots  is  notified  from  the  sulis.  if  a  previous  notification  has 
not  been  given.  •  When  a  ranging  shot  is  fii'ed  the  spotter 
sends  down  the  spot  by  visual  iiulicator,  telepluine.  and  voice 
tube  and  directs  "fire  second  ranging  shot"  or  "open  salvo," 
as  necessary.  The  chief  fire-control  officer  is  informeil  of  the 
spotter's  first  correction,  the  spot  is  given  to  the  plotters,  who 

3477fi-^-1S 15 


226  GUNNERY  INSTRUCTIONS. 

make  their  corrections  and  pass  the  result  to  the  range-clock 
man. 

As  soon  as  any  change  in  range  or  deflecion  is  sent  out  by 
the  visuals  to  the  turrets,  "set"  is  called  out  from  the  sub- 
central  over  the  J.  B.  phone.  If  no  change  is  to  be  made,  the 
word  "set"  or  "no  change"  is  called  out  immediately. 

As  soon  as  the  chief  tire-control  officer  gets  the  word  "open 
salvo,"  as  described  above,  he  orders  the  salvo  signals  begun. 
The  person  controlling  the  salvo  signals  wears  a  phone  and 
waits  for  the  word  "set"  from  the  subcentral,  then  sounds  the 
bells  and  buzzers  in  accordance  with  the  prearranged  plan. 

If  it  is  found  that  the  rate  of  change  obtained  does  not  keep 
the  salvos  straddle  of  the  target,  the  plotted  line  is  changed 
one-half  the  change  indicated  by  the  spots.  No  changes  in 
range  are  sent  out  to  the  turret  after  a  "stand-by"  signal 
unless  a  change  of  more  than  ]00  yards  is  required,  m  which 
case  the  subcentral  directs  "hold  the  fire,"  and  the  salvo- 
control  officer  holds  the  fire  until  he  hears  "set." 

Each  turret  employs  a  definite  system  in  locally  controlling 
the  fire.  Some  latitude  is  given  to  the  turret  officers,  and 
minor  features  vary  somewhat  in  turrets,  although  the  gen- 
eral scheme  is  the  same  for  all.  In  each  turret  are  three 
salvo  bells  and  three  buzzers,  one  bell  and  one  buzzer  near 
each  elevating  pointer  and  one  bell  and  buzzer  in  the  turret 
officer's  booth.  Thus,  each  elevating  pointer  and  the  turret 
officer  are  notified  simultaneously  regarding  salvos.  In  the 
turret  officer's  booth  are  sets  of  switclies,  one  for  signal  lights 
and  one  for  firing  circuits.  In  case  single-barreled  salvos 
are  used,  the  turret  officer  throws  a  double-throw  switch, 
which  flashes  a  light  close  to  the  eye  of  the  pointer  of  the 
gun  designed  to  fire  and  another  overhead  in  the  rear  of  the 
opposite  gun,  thus  notifying  the  opposite  gun  that  the  other 
1:?  to  fire.  In  case  double-barreled  salvos  are  used,  the  turret 
officer  flashes  the  light  close  to  the  eye  of  the  firing  pointer 


GUNNERY  INSTRUCTIONS.  227 

ai>d  throws  the  necessary  firing-circuit  switch  to  fire  double 
barreled.  In  case  it  is  desired  to  cut  out  a  turret  or  turrets, 
the  necessary  switclies  are  thrown  by  salvo  operator  in  fire- 
control  station,  and  consequently  bells  and  buzzers  are  not 
rung  in  the  turret  or  turrets  cut  out. 

424.  Cease  firing. — At  "  cease  firing  "  the  chief  fire-control 
officer  directs  "cease  firing"  over  the  telephone.  The  word 
is  passed  over  voice  tubes  and  phones  to  turrets,  and  "cease" 
is  displayed  on  visuals.  Tlie  salvo  signals  are  stopped,  and  the 
"cease  fii-ing"  gongs  are  rung  from  the  fire-control  station. 

425.  Torpedo  firing. — The  course  and  speed  of  the  enemy 
are  tracked  and  the  results  sent  to  the  torpedo-director  officer, 
who  keeps  the  directors  set,  so  that  torpedoes  may  be  fired 
at  any  time. 

TORPEDO  DEFENSE. 

426.  Personnel  of  group  control  parties. — Each  group  has 
an  independent  fire-control  party  as  follows: 

One  officer,  spotter. 

One  officer  in  charge  of  searchlight  control. 

One  range  keeper  and  talker. 

One  petty  officer  or  man  to  operate  distant  control  of  search- 
light. 

One  spotter's  lookout. 

Each  group  Is  equipped  with  telephones  and  voice  tubes, 
each  gun  and  fire-control  group  having  its  own  circuit.  Each 
has  a  searchlight  assigned  to  it,  and  a  crew  consisting  of  a 
man  and  helper  who  focus  the  light  and  stand  by  to  elevate 
iind  train  as  necessary  in  case  distant  control  fails  to  func- 
tion. 

The  system  is  elastic  and  the  eight  groups  (four  on  a  side) 
may  be  combined  at  discretion.  Each  group  is  entirely  in- 
dependent of  every  other  group  except  as  regards  salvo  sig- 
nals unless  combined. 


228  GTTWNERY  INSTRUCTIONS. 

427.  Operation  of  system. — The  chief  fire-control  officer 
and  assistant  fire-control  officers  are  stationed  on  the  bridge. 
The  former  gives  orders  directly  to  the  assistant  fire-control 
officers.  These  officers  wear  the  telephones.  An  officer  or 
petty  officer  operates  the  master  key  for  controlling  the  salvo 
signals,  which  enable  the  guns  in  all  groups  to  fire  at  the 
same  time.  The  operator  of  the  master  key  give*  two  short 
rings  shortly  before  firing  to  "stand  by,"  and  a  prolonged  ring 
to  "fire."  During  this  prolonged  ring  all  guns  i-eceiving  the 
signal  fire  when  "on."  Attempt  is  not  made  to  fire  all  guns 
simultaneously  as  this  would  interfere  with  accurate  shoot- 
ing. The  time  of  the  firing  interval  is  regulated  by  the  chief 
fire-control  officer. 

The  officer  in  charge  of  a  group  receives  the  order  "com- 
mence firing"  from  the  chief  fire-control  officer.  The  group 
spotter  then  orders  a  certain  gun  of  his  group  to  fire  ranging 
shots,  the  talker  passing  the  word  to  the  gun  designated,  to- 
gether with  the  initial  range  and  deflection. 

After  firing  sufficient  ranging  shots  to  get  on,  the  sights  of 
all  guns  being  kept  corrected,  the  group  spotter  orders  "open 
salvo."  The  order  is  passed  down  by  the  talker  to  all  guns 
of  the  group.  When  order  "open  salvo"  is  given  the  group 
spotter  closes  the  group  key,  and  the  guns  of  that  group 
receive  the  salvo  signal  when  the  master  key  is  operated  from 
the  bridge.  In  case  it  is  desired  to  have  the  guns  of  a  group 
cease  firing,  or  it  is  desired  to  again  fire  with  an  individual 
gun,  the  group  key  is  opened,  and  the  salvo  signals  cease  and 
the  necessary  instructions  are  sent  to  the  gun  or  guns  over 
the  lines  of  communication  by  the  group  fire-control  officer. 
By  this  means  an  individual  and  elastic  means  of  control  is 
provided. 

As  the  spotter  for  each  group  sings  out  a  spot,  the  talker 
applies  it  to  the  range  and  deflection  board  which  lie  holds  in 


GUNNERY  INSTRUCTIONS.  229 

his  hands  and  passes  the  corrected  range  and  dellectiou  to  the 
group  of  guns. 

Each  gun  should  have  a  standard  range  and  deflection  for 
zone  fire,  at  which  sights  shoukl  be  set  and  maintained  when- 
ever quarters  are  sounded  for  torpedo  defense,  until  other 
ranges  and  dedectious  are  ordered.  Attention  is  invited  to 
the  advisability  of  firing  short  rather  than  over. 


CHAPTER  19. 
ERRORS  OF  GUNFIRE. 

The  following  is  a  reprint  of  Ordnance  Pumphlet  No.  409,  of 
August,  1912,  on  Dispersion  and  Errors  of  Gunfire,  witli  minor 
additions : 

428.  Dispersion,  elements  of.— On  investigation  it  will  be 
found  that  all  the  errors  that  exist  in  gunfire  may  be  grouped 
under  two  heads: 

I.  Range  errors  and  lateral  errors. 

II.  Dispersion  errors,  both  vertical  and  lateral. 

I.  It  is  convenient  to  call  the  range  errors  and  lateral  errors 
"  Fire-control  errors,"  as  their  values  are  dependent  largely  on 
fire  control.  Even  if  it  were  possible  to  have  no  dispersion 
there  would  always  be  fire-control  errors.  The  magnitude  of 
these  errors  may  be  obtained  from  target-practice  records. 
Without  discussing  these  errors  it  is  important  to  understand 
that  no  matter  what  the  dispersion  errors  are,  the  fire-control 
errors  should  be  kept  as  small  as  possible  to  insure  the  maxi- 
mum hitting. 

II.  Dispersion  errors  will  always  exist.  They  are  due  to 
many  causes,  the  principal  of  which  are : 

(rt)  Variations  in  the  powder,  projectile,  cartridge  case, 
primer,  etc. 

{b)   Variations  in  the  gun. 

(c)  Variations  in  sight,  and  mounting. 

(d)  Personal  errors  of  pointers  and  sight  setters. 

The  various  elements  of  these  dispersions  will  be  taken  up 
in  order. 

429.  Powder  errors: 

1.  Variation  in  weight  of  charge. 

2.  Variation  in  temperature  of  charge. 
230 


GUNNERY  INSTRUCTIONS.  231 

3.  Variation  in  density  of  loading. 

4.  Hygroscopic  condition. 

5.  Variation  in  age  of  powder. 

6.  Imperfect  blending, 

7.  Variation  In  indexes. 

8.  Variation  in  weight  and  distribution  of  ignition  charge. 

9.  Variation  in  form  of  charge. 

10.  Unsuitability  of  powder. 

11.  Variation  in  muzzle  velocities. 

430.  Variation  in  weight  of  charge. — A  variation  in  the 
weight  of  charge  may  occasion  a  large  variation  in  pressure, 
giving  a  large  error  in  muzzle  velocity. 

Great  care  is  taken  in  establishing  the  correct  weight  of 
charges  assigned  to  the  various  guns.  Especial  care  is  taken 
in  the  magazines  in  assembling  the  weight  of  charge  cor- 
rectly, but  it  may  happen  through  some  mischance  that  either 
the  wrong  powder  or  the  wrong  weight  of  charge  Is  used  in 
the  gun.  Every  precaution  should  be  taken  to  prevent  this, 
as  aside  from  introducing  dispersion  a  small  increase  in 
weight  of  charge  may  occasion  dangerously  high  pressures. 

431.  Variation  in  temperature  of  charge.— All  powder 
charges  are  "  fixed  "  at  a  uniform  temperature  of  90°  F.,  the 
temperature  closely  approximating  to  that  of  magizines  on 
board  ship. 

It  will  be  found  that  if  the  temperature  varies  from  90°  F. 
errors  will  be  occasioned  in  the  initial  velocity. 

Tests  were  conducted  at  the  naval  proving  ground  with 
4-inch  .50-caliber  Mark  VIII,  5-inch  50-caliber  Mark  VI,  and 
8-inch  45-caliber  Mark  VI  guns,  to  determine  the  size  of  this 
error.  From  the  appended  sketches  A  and  B  it  will  be  seen 
that  for  small  variations  from  90°  F.,  a  change  of  1°  F.  in  the 
temperature  will  occasion  a  change  in  the  initial  velocity  of 
about  2  foot-seconds. 

It  is  not  important  that  the  magazines  should  be  kept  at 
90°  F.,  but  it  is  very  important  that  all  magazines  should  have 


232 


GUNNERY  INSTRUCTIONS. 


the  same  temperature,  or  that  proper  allowance  be  made  where 
temperatures  differ.  It  could -readily  happen  that  one  maga- 
zine was  10°  F.  hotter  than  another.  This  increase  in  tem- 
perature will  cause  an  increase  in  initial  velocity  of  20  foot- 
seconds,  producing  in  a  12-inch  2,700  foot-second  gun  a  vertical 


/>/)/ iJ)fAVAL  F^ov/j yg  (}!?ofy/fD  Bl. uEH^inT 


BiA  OF  t  ')ffDn  ANCi  -  >VJ?. 


3ar^9. 


N^  f4Z  May?  /9j2 


error,  at  10,000  yards,  of  about  35  feet.  It  is  evident  that 
this  error  is  very  serious  and  that  every  effort  should  be  made 
to  keep  the  temperatures  of  magazines  uniform. 

It  is  important  that  the  temperature  of  magazines  be  not 
only  the  same,  but  that  the  powder  should  have  attained  unl- 


GUNNERY   INSTRUCTIONS. 


233 


form  temperature  throughout.  At  the  naval  proving  ground 
a  powder  heated  19  hours  gave  30  foot-seconds  less  velocity 
than  when  heated  24  hours,  although  the  thermometer  in  each 
case  registered  90°  F. 


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432.  Variation  in  density  of  loading. — In  general  an  in- 
crease in  the  density  of  loading  occasions  an  increase  in  the 
pressure  and  an  increase  in  the  initial  velocity.  With  the 
projectile  properly  seated  and  the  correct  weight  of  powder 
charge  the  density  of  loading  is  constant  and  should  occasion 
no  error. 


234  GUNNERY  INSTRUCTIONS. 

The  density  of  loading  is  different  in  different  guns,  but 
no  error  is  introduced  tlirougli  this  cause,  as  the  weight  of 
charge  and  the  density  of  loading  are  Interdependent,  and  any 
error  in  the  density  of  loading  is  eliminated  when  the  charge 
for  a  gun  is  fixed. 

As.  a  gun  erodes  the  projectile  seats  farther  down  the  bore, 
and  a  decrease  in  the  density  of  loading  occurs,  causing  a 
falling  off  in  pressure  and  velocity. 

The  density  of  loading  a  gun  is  given  by  the  formula 

^^  WX27.68 


Volume  of  chamber  (in  cubic  inches) 
in  which  w=weight  of  charge  in  pounds. 

For  a  long  time  it  was  considered  that  a  density  of  loading 
of  about  0.5  was  correct  for  nitrocellulose  powder.  It  was 
deemed  necessary,  in  order  to  secure  proper  inflammation  of 
the  charge,  to  have  considerable  air  space  around  the  powder. 
Further  experience  has  shown  that  much  higher  densities  of 
loading  can  be  used.  It  is  not  possible  from  present  expe- 
rience to  state  what  the  maximum  allowable  density  of  load- 
ing should  be.  A  high  density  of  loading  should  be  avoided 
with  quick  powder  tis  erratic  pressure^?  are  likely  to  be 
produced,  but  if  slow  powder  is  used  the  pressures  are  re- 
liable. 

The  following  satisfactory  densities  of  loading  have  been 
obtained :  Six-pounder  gun,  0.80 ;  3-inch  field  gun,  0.77 ;  5-inch 
.40-caliber  gun,  0.72. 

The  greatest  density  of  loading  obtained  in  any  gun  in 
service  is  about  0.G7.  In  bag  guns  the  density  of  loading  is 
limited  by  the  design  of  the  powder  chamber  and  the  breech 
opening.  To  facilitate  loading  there  must  be  a  definite  clear- 
ance between  the  diameter  of  the  powder  bag  and  the  smallest 
diameter  of  the  gas-check  seat.  With  cylindrical  charges  for 
good  loading  conditions  this  clearance  should  be  about  0.75 
inch,  and  not  less  than  0.5  inch. 


GUNNERY  INSTRUCTIONS. 


235 


The  following  table  shows  the  effect  on  pressure  and  ve- 
locity of  changing  the  density  of  loading. 


Charge. 


31  pounds.. 

32  pounds.. 
35  pounds.. 
37.5  pounds 
40  pounds.. 


6-in?h  .50-caliberKun,No. 
338,  chamber  75.4  cubic 
inches  larger  than  No. 
353. 


Pressure. 


Tons. 
11.8 
13.4 
15.3 
17.4 
19.4 


Initial 
velocity. 


Foot-seconds. 
2,439 
2,  .567 
2,704 
2,842 
2,984 


6-inch  .50-ca!ibergun,  No. 
3-i3,  chamber  of  stand- 
ard size. 


Pressure. 


Tons. 
12.6 
14.6 
16.3 
18.9 
20.9 


Initial 

velocity. 


Foot-seconds. 
2,488 
2,630 
2,785 
2,949 
3,022 


433.  Hygroscopic  condition. — There  should  be  little  varia- 
tion due  to  hygroscopic  condition  of  powder  if  the  powder  is 
kept  in  air-tight  tanks  and  is  not  exposed  until  shortly  before 
it  is  fired. 

As  an  extreme  case,  the  following  test  was  conducted  to 
show  the  effect  of  moisture  on  the  powder  charge.  The  test 
was  conducted  in  a  5-inch  50-caliber  gun,  with  a  weight  of 
charge  of  25  pounds.  Two  charges  were  dampened  by  immer- 
sion in  water,  the  free  water  being  drained  off. 


5-inch  50-caliber  guns  (charge  25  pounds). 


Powder. 


Dry..., 
Do 

Damp. 
Do 


Tempera- 
ture. 

Pressure. 

Tons. 

60°  F. 

13.7 

60°  F. 

13.8 

60°  F. 

11.0 

60°  F. 

11.5 

Initial  velocity. 


Foot-seconds. 
|^f,^}MeanI.  V.=  2,795. 

^•^j^}MeanI.  V.=  2,628. 


236  GUNNERY  INSTRUCTIONS. 

It  should  be  understood  that  the  foi'egoing  test  is  not  com- 
parable to  that  of  a  powder  which  has  deteriorated  through 
exposure  to  moisture.  The  test  is  merely  to  show  the  differ- 
ence in  pressure  and  velocity  between  wet  and  dry  powder.  ' 
Powder  exposed  to  moisture  deteriorates,  and  of  course  loss 
of  pressure  and  velocity  depend  upon  the  extent  of  the  de- 
terioration. 

The  slowing  down  of  the  powder  in  the  test  referred  to  is 
due  entirely  to  the  absorption  of  moisture,  and  this  absorp- 
tion would  become  greater  with  powder  in  which  the  vola- 
tiles  were  low. 

434.  Variation  in  ag'e  of  powder. — As  powder  ages  it  gen- 
erally loses  some  of  its  volatiles  and  the  thickness  of  the  web 
decreases  slightly.  This  results  in  making  the  powder  some- 
what quicker,  giving  increased  pressure,  with  a  small  change 
in  muzzle  velocity. 

If  all  the  powder  of  an  index  is  subjected  to  the  same  con- 
ditions of  stowage,  however,  the  change  in  velocity  will  be 
uniform  throughout.  It  is  considered  that  no  error  is  intro- 
duced by  ageing  of  powder  on  board  ship,  provided  the  powder 
passes  satisfactory  tests,  althougli  the  velocity  and  pressure 
may  differ  from  that  on  proof.  If  the  powder  should  begin 
to  deteriorate,  large  errors  would  be  occasioned  in  muzzle 
velocities,  but  the  tests  on  board  ship  would  detect  this  dete- 
rioration and  prevent  the  use  of  this  powder.  The  life  of 
powder  depends  very  largely  on  the  conditions  of  stowage. 
The  average  life  of  an  index  under  fair  stowage  conditions 
may  be  taken  as  about  10  to  12  years.  With  stabilized  powder 
the  life  will  probably  be  20  years. 

It  is  very  important  that  the  powder  tanks  and  cartridge 
cases  be  kept  air-tight,  so  as  to  maintain  stowage  conditions 
similar.  The  life  of  powder  is  lengthened,  too,  by  keeping  the 
tanks  air  tight.     (See  art.  2S03  (1),  Naval  Instructions,  1913.) 

435.  Imperfect  blend. — Before  powder  is  tested  and  as- 
signed to  service  it  is  thoroughly  blended.    It  is  found  in  the 


GTINNERY  INSTRUCTIONS.  237 

manufacture  of  powder  that  the  different  lots  vary  slightly 
in  nitration  and  to  some  extent  in  volatiles.  Several  lots  are 
blended  into  one  Index  before  being  proof  fired.  The  blends 
give  very  uniform  results,  and  there  'should  be  little  or  no 
error  resulting  from  this  cause.  If  an  imperfect  blend  were 
made  of  widely  dissimilar  powders,  large  variations  would  be 
obtained  in  initial  velocities,  depending  upon  the  dissimilarity 
of  the  powders  blended  and  the  imperfect  blending.  These 
conditions  do  not  obtain,  however,  in  the  powders  issued  to 
service. 

436.  Variation  in  indices. — It  should  be  understood  that 
the  foregoing  remarks  (item  1-6)  apply  to  any  one  index  of 
powder.  The  difference  in  the  temperature,  age.  etc.,  of  any 
index  will  produce  a  variation,  but  the  whole  index  should  be 
similarly  affected.  If,  however,  part  of  the  firing  of  a  gun 
is  done  with  one  index  of  powder  and  part  with  another,  there 
may  be  introduced  an  additional  eri-or,  due  to  using  the  dif- 
ferent indices. 

With  all  the  care  in  manufacture  and  inspection  that  ob- 
tains, it  is  found  that  it  is  impracticable  to  make  the  different 
indices  exactly  alike;  in  fact,  an  index  is  simply  the  blending 
of  a  number  of  lots  of  powder.  Different  indices  require  dif- 
ferent weights  of  charge  to  give  service  velocity.  In  fixing  the 
weights  of  charge  of  different  indices  to  give  service  velocity 
there  is  likely  to  be  a  small  error,  which  should  not  exceed, 
however,  about  one-half  of  1  per  cent  of  the  muz.zle  velocity. 

In  addition  to  this  error,  the  different  indices  may  not  be 
similar  as  regards  temperature,  age,  etc.  The  use  of  addi- 
tional indices  introduces  more  errors.  It  would  be  desirable, 
of  course,  on  board  ship  to  have  only  one  index  of  powder  for 
each  caliber  of  gun,  but  this  is  not  practicable.  Provision 
should  be  made  in  fire  control  for  using  different  indices.  One 
index  should  be  exhausted  before  firing  is  taken  up  with  the 
next  index.  Any  variations  occurring  in  the  new  index  could 
then  be  compensated  for  by  the  spotter. 


238 


GUNNERY  INSTEUCTIONS, 


437.  Variation  in  weight  and  distribution  of  ignition 
charge. — There  should  be  no  variatioa  from  this  cause  in 
the  powders  assigned  to  service.  Numerous  tests  have  been 
conducted  to  establislt  the  correct  weight  of  ignition  to  give 
proper  inflammation.  This  weight  is  now  standardized  for 
the  various  calibers  of  guns.  To  show  tlie  effect,  liowever, 
of  varying  the  weight  of  ignition  charges,  the  following  data 
are  given.  It  will  be  noted  from  these  data  that  there  is 
considerable  variation  in  pressure  and  velocity  occasioned  by 
using  different  Aveights  of  ignition  charge. 


Ignition  charge. 


6-inch  SO-caliber  B.  L.  R.  {same  weight  of  charge  through 
out). 

100  grams  at  breach  end  of  charge 

Do 

3  ounces  at  each  end  of  charge 

Do 

6  ounces  at  each  end  of  charge 

Do 

8-inch  33-caliber  B.  L.  R.  (charge,  5S  pounds). 

Regular  ignition,  14  grains 

Do 

Do 

7  grains  each  end  of  each  section— 29  grains  in  all 

1-2-inch  iO-caliber  B.  L.  R.  {charge,  346  pounds). 

Ignition  at  each  end  of  each  section 

Total,  6.92  pounds 

Usual  ignition 


Pressure. 


Velocity. 


Tons. 

Foot-secondx. 

18.85 

2,914 

18.80 

2,907 

19.60 

2,927 

19.50 

2.924 

19.80 

2,922 

20.10 

2,923 

12.03 

2,098 

12.06 

2,108 

12.60 

2,098 

12.06 

2,128 

17.15 

2,754 

17.61 

2,768 

18.25 

2,806 

438.  Variation  in  form  of  charge. — There  should  be  no 
variation  from  this  cause  in  service,  as  a  definite  form  of 
charge  is  adopted  for  each  gun.  Tests  have  been  made  at  the 
naval  proving  ground  to  determine  whether  better  results  are 
obtained  with  the  charge  put  up  in  a  large  or  a  smaller  num- 
ber of  bags.     Little  variation  in  either  pressure  or  velocity 


GUNNERY  INSTRUCTIONS.  239 

resulted,  however,  provided  sufficient  weight  of  ignition  was 
added  to  the  charge. 

439.  Unsuitability  of  powder. — In  general,  it  is  the  inten- 
tion that  all  powder  should  be  consumed  in  the  gun,  but  it 
sometimes  happens  that  unburned  powder  is  blown  from  the 
gun.  This  condition  is  approaclied  in  most  modern  guns  in 
the  effort  to  get  a  high  muzzle  velocity  without  undue  maxi- 
mum pi-essure.  It  is  evident  that  the  same  velocity  could  be 
obtained  with  a  quicker  powder,  giving  a  higher  maximum 
pressure,  and  this  condition  tends  to  give  more  uniform  muz- 
zle velocities:  but  the  maximum  pressures  are  kept  down  in 
the  effort  to  retluce  erosion.  In  all  but  especial  cases,  how- 
ever, the  whole  charge  should  be  consumed  in  the  gun. 

It  becomes  a  delicate  matter  to  get  a  powder  that  will  give 
the  velocity  required  and  still  keep  below  the  maximum  pres- 
sure allowed.  It  frequently  happens,  too,  that  owing  to  the 
unsuitable  design  of  a  gun  it  is  difficult,  if  not  impossible,  to 
select  for  that  gun  a  thoroughly  efficient  powder.  The  selec- 
tion of  the  most  suitable  web  thickness  is  further  complicated 
by  the  fact  that  in  two  similar  powders  of  the  same  web 
thickness  there  may  be  considerable  variation  in  volatiles,  or 
other  characteristics,  causing  considerable  differences  in  bal- 
listic properties. 

440.  Variation  in  muzzle  velocities. — It  is  found  that  with 
conditions  as  nearly  perfect  as  they  can  be  made  there  re- 
sults nonuiiiformity  of  muzzle  velocities.  The  first  round 
fired  may  show  2,700  foot-seconds  and  the  next  round  2,710 
foot-seconds.  This  variation  in  velocities  results  mostly  from 
Ihe  nonuniformity  of  the  burning  of  the  powder,  although 
other  causes  contribute  to  it,  as  will  hereafter  be  seen. 

In  general,  it  may  be  said  that  the  average  variation  in 
muzzle  velocity  is  less  than  one-half  of  1  per  cent  of  the  aver- 
age velocity.  If  the  average  of  10  shots  gives  2,800  foot-sec- 
onds, it  is  not  to  be  expected  that  the  average  shot  will  vary 
more  than  ±14  foot-seconds,  although  particular  shots  may 


240 


GUNNERY  INSTRUCTIONS. 


have  greater  variation.  lu  fact  ±  one-half  of  1  per  cent  is 
about  the  greatest  mean  variation  of  any  powder  in  service. 

The  following  table  shows  the  average  variation  from  the 
mean  in  the  muzzle  velocities  of  a  few  guns  and  powders. 
These  variations  change  with  the  different  powders  tested. 

14-inch,  45-caliber,  2,600  foot-seconds,  mean  of  9  sliots,  gave 
±3  foot-seconds. 

12-inch,  50-caliber.  2,900  foot-seconds,  mean  of  11  shots,  gave 
±11  foot- seconds. 

10-inch,  4()-caliber,  2,700  foot-seconds,  mean  of  5  shots,  gave 
±5  foot-seconds. 

8-inch,  4.5-caliber.  2,750  foot-seconds,  mean  of  11  shots,  gave 
±4  foot-seconds. 

7-inch,  45-caliber,  2,700  foot-seconds,  mean  of  6  shots,  gave 
±11  foot-seconds. 

6-inch,  50-caliber.  2.800  foot-seconds,  mean  of  24  shots,  gave 
±8  foot-seconds. 

The  effects  at  6,000.  9,000,  and  12,000  yards  are : 


14-inch  45-ealiber 
12-inch  50-caliber 
10-inch  40-caUber 
8-inch  45-caliber. 
7-inch  45-caliber . 
6-inch  sa-caliber. 


Service. 


2,600±  3 
2,000±11  I 
2,700±  5  ' 
2,750±  4 
2,700±11 
2,800±  8 


6,000 

9,000 

Yards. 

Yards. 

11 

16 

1              39 

56 

i              18 

26 

1              14 

19 

37 

50 

25 

34 

12.000 


Yards. 


21 

70 
32 
23 
60 
39 


441.  Reduced  ch.arg'es. — Reduced  charges  are  fixed  by  se- 
lecting weiglits  whicli  at  the  proving  grounds  actually  give 
desired  reduced  velocity.  For  12-inch  they  have  hitherto  been 
made  up  in  tin-ee  sections  instead  of  four.  l)ut  with  one-third 
more  ignition  in  each  so  that  the  total  ignition  is  the  same  as 
for  service.  The  Bureau  of  Ordnance  is  considering  the  ad- 
visability of  making  up  reduced  charges  in  four  sections,  with 
bags  of  service  length,  but  less  girth.    This,  however,  is  merely 


GUNNERY  INSTRUCTIONS.  241 

H  matter  of  whether  the  full  number  of  sections  is  better  for 
drill  purposes  tluiu  getting  approximately  service  weight  in 
each,  but  with  one  less  section.  The  velocity  would  be  the 
same  in  either  case,  but  there  would  be  the  advantage  of  the 
larger  bag  being  necessarily  closer  to  the  mushroom,  and 
rherefoi-e  more  certainly  ignited. 

442.  Unconsumed  powder. — Powder  burns  with  increasing 
surface  until  the  holes  enlarge  into  each  other.  Slivers  are 
formed,  some  with  three  concave  sides  from  the  inside  web. 
and  others  with  two  concave  and  one  convex  side  from  the 
outside  web.  These  burn  with  diminishing  surface,  and  this 
fact  (especially  since  formed  when  the  projectile  is  moving  so 
fast)  makes  their  contribution  to  the  energy  of  the  projectile 
relatively  quite  ineflicieut.  In  delaying  their  formation  as 
long  as  possible,  it  is  sometimes  found  advisable  to  use  the 
heavier  charge,  burn  it  with  inci'easing  surface  until  very 
late,  and  let  the  slivers  go.  In  certain  guns,  notably  Army 
mortars,  this  is  the  rule  rather  than  the  exception.  Uncon- 
sumed powder  outside  of  a  gun  does  not  mean  low  velocity 
because  of  that  amount  of  powder  having  been  depended  upon 
to  burn.  It  is  expedient  to  use  the  same  web  for  reduced 
charges,  and  in  most  cases  more  of  it  remains  unburned  than 
with  a  full  charge.  More  powder  generates  pressure  quicker, 
and  this  pressure  in  turn  quickens  the  burning  enough  to 
burn  up  an  even  larger  amount  of  powder.  Both  service  and 
retluced  charges  can  give  no  velocity  errors  because  of  leav- 
ing unconsumed  powder,  for  they  have  been  actually  fired  at 
the  proving  ground  and  give  the  stated  velocities  without 
regard  to  unconsumed  powder. 

443.  Projectiles: 

1.  Variation  in  weight. 

2.  Variation  in  diameter  of  bourrelet. 

3.  Variation  in  rotating  bands, 

4.  Variable  form  of  projectile. 
.'i4776— 18 16 


242  GUNNERY  INSTRUCTIONS. 

5.  Position  of  center  of  gravity. 

6.  Projectiles  not  concentric  witli  bore  of  gun. 

444.  Variation  in  weight. — Tliere  may  be  a  variation  in 
tlieweiglitof  the  projectiles  used.  Tlie  standard  weight  of  pro- 
jectiles includes  the  weight  of  the  bursting  charge.  The  error 
introduced  by  firing  projectiles  of  different  weights  is  not  very 
great  for  small  variations.  A  12-inch  projectile,  for  instance, 
3  pounds  overweight,  will  produce  at  10,000  yards  an  error  in 
range  of  but  12  yards.  This  is  an  error  which  can  be  readily 
eliminated,  however,  and  should  not  exist.  A  considerable 
variation  in  weight  would  produce  a  large  range  error. 

445.  Variation  in  diameter  of  bourrelet. — The  standard 
clearance  between  the  bore  of  the  gun  and  the  diameter  of 
the  bourrelet  of  the  projectile  is  0.015  inch  for  all  modern 
projectiles.  Some  of  the  older  projectiles  have  a  clearance  of 
0.05  inch,  and  these  projectiles  should  not  be  fired  with  the 
later  ones. 

It  has  generally  been  assumed  that  the  smaller  clearance 
gives  better  flight,  but  the  variation  to  be  expected  within  the 
small  limits  mentioned  has  not  been  establifhed.  It  has  been 
shown,  however,  that  projectiles  centered  by  means  of  a 
bourrelet  give  more  efficient  flight  than  those  which  are  not 
so  centered,  the  coefficient  of  form  being  reduced  by  about 
5  per  cent. 

446.  Variation  in  rotating  bands. — If  rotating  bands  on 
projectiles  differ  either  in  width,  thickness,  or  form  there 
may  be  occasioned  a  variation  in  pressiire  and  muzzle  velocity. 
In  general,  if  the  forcing  is  increased— that  is,  if  more  copper 
is  to  be  engraved — there  will  result  an  increase  of  breech 
pressure  and  a  decrease  in  muzzle  pressure.  The  error  in 
muzzle  velocity  may  be  slight,  but  in  general  increased  forc- 
ing will  cause  an  increase  in  the  muzzle  velocity. 

The  following  tests  were  made  at  the  naval  proving  ground 
to  determine  the  effect  of  using  various  types  of  rotating  bands 
In  different  guns: 


GUNNERY  INSTRUCTIONS. 


243 


In  a  12-inch  35-caliber  Mark  II  gun  having  depth  of  rifling 
of  0.05-inch  projectiles  were  fired  having  rotating  bands  of 
standard  width,  but  increased  in  thicliness  from  12.12  to  12.17 
inches.  Tlie  cross-sectional  increase  in  copper  to  be  engraved 
was  from  1.35  square  inches  to  2.47  square  inches.  There 
resulted  an  increase  in  the  pressure  of  O.S  ton.  There  was 
little  change  in  velocity. 

A  similar  test  was  held  in  12-inch  45-caliber  Mark  VI  gun, 
in  which  the  depth  of  rifling  was  0.05  inch.  There  resulted  in 
this  gun  an  increase  in  pressure  of  0.4  ton,  causing  an  in- 
crease in  the  velocity  of  22  foot-seconds. 

Tests  were  also  conducted  in  14-inch  45-caliber '  Mark  I 
gun,  with  depth  of  groove  of  0.075  inch.  Bands  of  similar 
width,  but  of  standard  thickness,  14.175  inches  and  of  di- 
minished thickness,  14.122  inches,  were  fired.  Thei'e  resulted 
a  decrease  in  the  standard  pressure  of  about  1  ton,  with  no 
change  in  velocity. 

A  similar  test  was  conducted  with  12-inch  50-caliber  Mark 
VII  gun,  with  depth  of  rifling  0.075  inch.  The  banris  were 
the  same  width ;  one  was  of  standard  thickness,  12.18  inches, 
and  one  of  diminished  thickness,  12.12  inches.  The  thin  band 
caused  a  drop  in  pressure  of  0.7  ton,  with  a  loss  in  velocity 
ol  37  foot-seconds. 

Tests  of  a  6-inch  50-caliber  gun,  weight  of  charge  42* 
pounds,  gave  the  following  data : 


Diameter  of  band. 

Pressure. 

Velocity. 

Average. 

Inches. 
6.112 

Tonn. 
13.26 
15.30 
14.06 

Foot-seconds. 
2,802 
2,810 
2,822 

Foot-seconds. 

6.112 

2,811 

6.112 

6.112 

6.135 

14.03 
16.01 
16.04 

2,822 
2,825 
2,843 

6.136 

6.144 

244  GUNNERY  INSTRUCTIONS. 

It  should  be  undei'stood  that  these  tests  were  held  over  wide 
variations ;  but  as  there  are  in  service  guns  of  the  same  caliber 
having  different  depths  of  rifling,  it  might  well  happen  that 
rotating  bands  designed  for  one  rifling  were  inadvertently 
used  in  guns  having  a  different  depth  of  rifling.  If  thick  and. 
thin  rotating  bands  were  used  in  the  same  gun  it  is  evident 
there  might  be  wide  variations  in  pressure  and  muzzle  veloci- 
ties. All  bands  should  be  gauged  to  see  if  they  are  correct  for 
the  guns  in  which  they  are  to  be  fired. 

For  12-iuch  guns  there  are  some  12.12"  bands  in  service  and 
some  12.18".  Grooves  in  the  guns  are  0.05"  deep  or  0.075" 
deep  except  in  some  special  cases.  The  large  bands  go  with 
the  deep  grooves.  The  dimensions  are  the  body  of  the  band, 
the  lip  being  still  larger.  T.arge  bands  are  at  present  favored 
because  they  act  as  a  "  shell  stop,"  holding  the  shell  at  ap- 
proximately its  right  seating  even  in  a  worn  gun,  while  with 
a  smaller  band  the  same  amount  of  erosion  allows  the  shell  to 
ram  in  farther  and  lose  more  velocity.  From  firings  in  a  new 
12-inch  gun  with  0.12"  grooves  it  was  found  that  each  one 
one-hundredth  on  the  band  gave  an  additional  4.8  f.  s.  from 
12.12  to  12.18"  and  about  4.0  f.  s.  from  12.18  to  12.25",  so, 
among  shell  supposed  to  be  banded  alike,  ordinary  tolerances 
in  workmanship  can  give  no  appreciable  velocity  differences. 
Thicker  bands  increase  the  serviceable  life  of  the  gun,  as 
steady  flight  is  maintained  on  a  larger  number  of  rounds  with 
the  same  gun.  The  action  of  larger  bands  is  to  increase  the 
pressure  developed  before  the  shell  starts,  and  as  pressure 
accelerates  velocity  of  combustion  the  powder  is  burned  earlier 
throughout  than  normal.  It  thus  resembles  in  its  action  a 
powder  of  thinner  web  and  develops  additional  pressure  and 
velocity  more  than  sufficient  to  overcome  the  slightly  increased 
friction  of  the  band.  Provided  that  the  bands  do  not  strip 
and  that  the  muzzle  velocity  is  the  same,  they  can  have  no 
effect  on  flight,  because  all  sizes  come  out  of  the  gun  the  same 
diameter. 


GUNNERY  INSTRUCTIONS.  24a 

The  larger-sized  bands  often  fail  to  stick  in  the  seat  when 
the  gun  is  elevated,  but  a  single  rope  yarn  around  the  baud 
will  prevent  tleir  slipping  back.  Minor  changes  in  design  are 
being  undertaken  to  overcome  this  difficulty. 

447.  Form  of  projectile. — The  form  of  projectile  is  of  great 
importance.  The  outside  contour  of  all  the  projectiles  fired 
from  a  battery  should  be  the  same.  The  length  and  diameters 
should  be  alike  within  the  allowed  tolerances. 

The  effect  of  changing  the  form  of  the  point  of  the  projectile 
from  2-caliber  radius  to  7-caliber  radius  was  very  marked. 
There  resulted  an  increase  in  the  range  of  16  to  20  per  cent, 
with  all  the  attendant  advantages. 

Tests  were  conducted  giving  the  projectile  a  still  sharper 
point,  with  a  radius  of  10  calibers.  This  resulted  in  a  further 
increase  in  the  range  of  about  7  per  cent.  This  increase,  how- 
ever, did  not  offset  the  disadvantages  of  the  longer  point. 

If  projectiles  of  the  same  weight  are  fired  with  different 
outside  contours  there  will  result  wide  variations  in  range. 
It  is  very  important  that  all  projectiles  fired  from  a  battery 
have  the  same  form. 

Owing  to  the  changes  which  have  taken  place  in  the  de- 
velopment of  projectiles,  it  may  happen  that  the  projectiles 
supplied  a  vessel  are  not  all  alike.  There  are  always  some 
(lilTerences  due  to  manufacturing  toleran<  o^  ovon  if  the  pro- 
jectiles are  otherwise  alike. 

448.  Position  of  center  of  gravity. — Variation  in  the  fore- 
and-aft  position  of  the  center  of  gravity  will  cause  variation 
in  range,  even  although  the  outside  contours  of  the  projectiles 
are  alike.  The  position  of  the  center  of  gravity  and  the  force 
of  the  resistance  of  the  air  determine  the  overturning  moment 
that  a  projectile  encounters  in  flight.  A  change  in  the  posi- 
tion of  the  center  of  gravity  will  change  this  overturning 
moment,  and  so  cause  a  variation  in  both  range  and  deflection. 
It  is  likely,  however,  that  this  error  is  small  for  small  varia- 
tions in  the  position  of  the  center  of  gravity.    Even  although 


246  GUNNEKY  INSTRUCTIONS. 

the  fore-and-aft  position  of  the  center  of  gravity  is  the  same 
in  projectiles,  it  may  be  eccentric  in  the  projectiles.  Eccen- 
tricity may  be  produced  by  a  liidden  cavity  in  the  steel,  or 
by  a  variation  in  wall  thickness.  Tests  are  made  to  detect 
any  eccentricity,  and  such  projectiles  are  rejected.  Any 
error  caused  by  a  small  eccentricity  ouglit  to  be  of  small 
magnitude. 

It  will  be  found  that  there  is  considerable  variation  in  the 
position  of  the  center  of  gravity  due  to  the  changes  in  the 
development  of  the  projectile,  use  of  different  fuzes,  different 
forms  of  cavity,  etc. 

449.  Projectiles  not  concentric  with  bore  of  ffun. — It  may 
happen,  especially  after  a  gun  is  somewhat  worn,  that  the 
projectile's  axis  is  not  concentric  with  that  of  the  bore  of 
the  gun.  There  is  always,  of  course,  a  slight  divergence,  due 
to  clearance  of  the  bourrelet  diameter,  but  this  may  be  aug- 
mented if  the  rotating  band  does  not  center  the  base  of  the 
projectile  in  the  bore  of  the  gun.  It  is  not  possible  to  tell 
how  great  this  variation  is,  but  it  is  likely  that  the  projectile 
rarely  leaves  the  gun  with  its  axis  in  the  exact  line  of  the 
bore  of  the  gun. 

CARTBIDGE  CASES,  PRIMERS,  ETC. 

450.  Cartridge  cases. — There  may  be  a  slight  variation  in 
the  capacity  of  cartridge  cases,  due  to  the  tolerances  allowed 
in  manufacture.  This  changes  the  density  of  loading,  and  so 
affects  pressures  and  velocities.  The  allowed  tolerances  in 
manufacture  are  as  small  as  they  can  practicably  be  made, 
and  any  error  resulting  from  this  cause  must  be  small. 

In  cartridge  cases  of  5-inch  and  6-inch  guns,  where  -the 
projectile  is  loaded  separately,  it  has  been  found  necessary 
to  have  a  mouth  cup  in  the  cartridge  case  to  prevent  the 
end  of  the  case  from  being  split  or  deformed  by  the  powder 
gas.    The  fitting  of  these  mouth  cups  has  a  considerable  effect 


GUNNERY  INSTRUCTIONS.  247 

on  velocities  and  pressures.  The  following  data  was  obtained 
from  firing  a  G-inch  40-caliber  gun,  weight  of  charge  17 
pounds : 

Using  a  distance  piece  and  a  felt  wad,  and  a  loose  mouth 
cup,  the  pressure  was  5.5  tons  with  a  velocity  of  1,598  foot- 
seconds.  With  the  charge  put  up  In  the  usual  way  with  a 
tight-fitting  mouth  cup,  the  pressure  was  6.6  tons,  and  the 
velocity  1,651  foot-seconds.  The  effect  of  the  loose-fitting 
mouth  cup  was  virtually  to  decrease  the  density  of  loading 
with  a  decrease  in  pressure  and  velocity.  The  variation 
shown  in  this  test,  however,  is  greater  than  may  be  expected 
in  service,  even  with  loose-fitting  mouth  cups,  as  the  mouth 
cup  is  in  general  not  more  than  about  1  inch  from  the  base 
of  the  projectile,  and  the  decrease  in  the  density  of  loading, 
due  to  the  loose-fitting  cup,  is  relatively  small. 

A  similar  variation  may  occur  in  guns  of  5-inch  caliber  and 
smaller,  due  to  the  projectiles  not  being  seated  alike  in  the 
cartridge  cases.  No  great  error  can  occur 'in  this  way,  how- 
ever, as  when  the  cartridge  case  is  loaded  in  the  gun  the 
projectile  will  likely  be  pushed  back  to  its  proper  place  in  the 
cartridge  case.  Any  unseating  of  the  projectile  would  cause 
a  decrease  in  the  density  of  loading,  with  consequent  falling 
ofE  in  pressure  and  velocity. 

451.  Primers. — There  is  considerable  difference  between 
the  speed  of  primers,  the  percussion  primer  being  much  faster 
than  the  electric  primer. 

Tests  were-  made  at  the  naval  proving  ground  with  an  8- 
inch/.35  gun.  using  Mark  VIII  lock.  Combination  primers 
were  tested  by  electric  firing  and  percussion  primers  by  per- 
cussion firing  and  the  time  intervals  measured.  With  com- 
bination primers  the  interval  from  the  moment  contact  was 
made  at  the  primer  until  the  flame  issued  from  the  mouth  of 
the  mushroom  was  0.031  second,  averaging  four  primers. 
These  primers  gave  intervals  of  firing  from  0.013  to  0.073 
second.    Two  other  primers  gave  intervals  of  0.040  and  0.030. 


248  GUNNERY  INSTRUCTIONS. 

A  similar  test  in  a  6-incli/50  gun  gave  for  an  average  of 
16  primers  an  interval  of  0.044  second.  It  is  believed  that  this 
figure  is  a  fair  average  for  electric  or  combination  primers. 

With  percussion  primers  the  interval  from  the  moment  con- 
tact was  made  at  the  primer  until  flame  issued  from  the  mush- 
room gave  0.004  second,  as  an  average  of  four  rounds,  the 
rounds  varying  from  0.003  to  0.004.  Two  other  rounds  gave 
0.0044  second  and  0.006  second. 

It  is  evident  from  the  foregoing  that  the  percussion  primer 
Is  much  faster  than  the  electric  primer,  and  so  far  as  concerns 
this  point  only  percussion  firing  is  more  desirable  than  elec- 
I  ric.  It  will  be  found,  however,  in  measuring  the  complete 
firing  interval  that  the  difference  between  the  electric  and  the 
percussion  intervals  is  very  small,  and  the  flexibility  of  elec- 
tric firing  makes  it  necessary  in  most  cases. 

452.  Firing  interval. — The  firing  interval  may  be  taken 
as  the  time  from  the  instant  when  the  pointer  wills  to  fire 
until  the  projectile  leaves  the  muzzle.  For  measuring,  this 
interval  has  been  divided  into  three  parts : 

(a)  Time  from  instant  when  pointer  wills  to  fire  until 
closing  of  firing  key  has  been  completed. 

(ft)  Primer  interval. 

{(')  Interval  from  flame  issuing  from  mushroom  until  pro- 
jectile leaves  muzzle. 

Item  («)  was  measured  at  the  naval  proving  ground.  The 
average  of  five  pointers  gave  0.179  ;  times  of  firing  from  0.138  to 
0.236.  With  a  firing  key  or  tripping  a  sear  the  interval  would 
evidently  be  the  same  whether  electric  or  percussion  firing  were 
used.  This  interval  varies  greatly,  depending  upon  the  per- 
sonality of  the  pointer,  a  slow  pointer  requiring  more  than 
the  average  interval.  It  is  believed  that  the  value  given  of 
0.179,  hov^ever,  is  a  fair  average  for  service  pointers. 

The  value  of  interval  (b)  has  already  been  stated. 

The  value  of  interval  (c)  varies  for  different  guns,  but  may 
be  taken  as  about  0.020. 


GUNNERY  INSTRUCTIONS.  248 

Adding  these  intervals,  it  will  be  found  tlmt  the  firing 
Interval  for  electric  firing  is  about  0.243  seconds,  while  that 
for  percussion  firing  would  be  about  0.203  seconds. 

It  is  evident,  therefore,  that  although  the  percussion  primer 
is  ten  times  as  fast  as  the  electric,  the  gain  in  the  firing  in- 
terval by  its  use  is  very  small. 

453.  Guns: 

1.  Variation  in  rifling. 

2.  Seating  of  projectile. 

3.  Density  of  loading. 

4.  Temperature  of  chamber,  bore.  etc. 

5.  Vibration  of  gun. 

6.  Variation  in  chamber  capacity. 

7.  EUipticity  of  bore. 

8.  Shell  leaving  bore  witli  its  axis  inclined. 

9.  Erratic  flight  of  shell. 

10.  Short  hangfire. 

454.  Variation  in  rifling'. — In  the  guns  of  a  battery  it  may 
happen  that  there  is  a  variation  in  muzzle  velocities  caused 
by  some  guns  being  rifled  differently  from  others.  The 
rifling  may  be  of  dilTerent  twist;  the  form,  depth,  and  num- 
ber of  grooves  may  differ,  and  the  amount  that  the  grooves 
are  narrowed  at  the  muzzle  may  differ.  All  of  these  varia- 
tions in  rifling  afl'ect  the  muzzle  velocities.  There  may  be  an 
error  from  10  to  25  foot-seconds  due  to  this  cause.  All  guns 
of  a  battery  should  be  rifled  alike,  and  this  condition  generally 
obtains,  but  the  twist  of  the  rifling  as  well  as  the  form,  dimen- 
sions and  number  of  grooves  have  been  changed  at  different 
times  for  various  reasons,  and  it  will  be  found  in  a  few  in- 
stances that  some  guns  of  a  battery  are  rifled  differently  from 
others. 

455.  Seating  of  projectile. — As  guns  erode  the  projectiles 
seat  farther  down  the  bore.  There  results  a  decrease  in  the 
density  of  loading,  with  consequent  falling  off  in  pressure 
and  velocity.     Tests  made  at  the  naval  proving  ground  show 


250  GUNNERY  INSTRUCTIONS. 

the  loss  of  velocity  to  be  expected  in  8-inch  45-caliber  Mark  VI 
guns,  and  12-inch  45-caliber  Mark  V  guns,  when  the  distance 
of  shell  seating  beyond  normal  is  known.  The  standard  shell 
seating  is  shown  on  the  drawings,  and  the  distance  the  shell 
seats  beyond  normal  can  readily  be  measured,  and  the  de- 
crease in  the  velocity  of  a  gim  can  be  estimated.  Projectiles 
used  in  these  tests  had  rotating  bands  with  lips  of  8".36  and 
12".30,  respectively.  If  larger  lips  are  used  the  protectiles 
will  not  seat  so  far  down  the  bore,  and  a  small  part  of  the 
loss  in  velocity  and  pressure  is  restored.  Practically  all  of 
this  loss  in  pressure  and  velocity  can  be  restored  by  using 
rotating  bands  of  proper  form  to  compenate  for  the  erosion. 

So  far  as  accuracy  of  fire  is  concerned,  it  is  important  only 
that  all  projectiles  used  should  be  alike,  and  that  in  firing, 
the  distance  from  the  face  of  the  tube  to  the  base  of  the 
projecile  should  be  he  same  in  the  guns  of  a  battery. 

Sketches  C  and  D  show  the  loss  of  velocity  to  be  expected 
in  8-inch  45-caliber  Mark  VI,  and  12-inch  45-caliber  Mark  V 
guns.  In  a  new  gun  there  may  be  a  considerable  error  in 
velocity  occasioned  by  the  projectile  not  being  home.  Numer- 
ous tests  have  been  made  to  ascertain  this  error,  and  it  is 
found  that  there  is  a  wide  variation  in  the  results  obtained. 
It  is  impossible  to  state  the  magnitude  of  this  error,  as  it  de- 
pends not  only  on  the  distance  of  the  projectile  from  normal 
seating,  but  also  on  the  design  of  the  powder  chamber,  and 
on  the  density  of  loading.  Sufficient  data  has  been  obtained 
to  show  that  it  is  important  for  accurate  fire  to  have  the 
projectile  seated  at  the  same  place  each  time.  In  general,  the 
projectile  not  being  home  causes  an  increase  in  the  density 
of  loading,  with  consequent  increase  in  pressure  and  velocity. 
In  some  types  of  powder  chambers,  however,  and  under  certain 
conditions  of  loading,  the  increase  in  density  of  loading  is 
more  than  offset  by  the  loss  of  gas  escaping  around  the  pro- 
jectile, and  there  results  a  decrease  in  pressure  and  velocity. 
The  error  occasioned  by  the  projectile  not  being  home  is  not  so 


GUNNERY  INSTRUCTIONS. 


261 


apparent  at  short-range  firing,  but  it  causes  serious  dispersion 
at  battle  ranges. 

The  following  data  is  from  tests  lield  at  the  naval  proving 
ground : 

6-inch  50-caliber  Mark  VIII  gun. 


Shell  not  home  by— 

Loss  pres- 
sure. 

Velocity. 

2.9  inches 

Tons. 
0.2 
.0 
.4 
1.2 
.9 
.8 

Loss,  3  foot-seconds. 

2.9  inches 

Increase.  7  foot-seconds 

2.9  inciies 

Increase,  9  foot-seconds. 

5.5  inches 

Increase  56  foot-seconds 

5.9  inches 

Increase.  32  foot-seconds. 

5.9  inches 

Loss.  44  foot-seconds. 

7-inch/45  Mark  II  gun,  v^^ith  shell  properly  seated,  gave  a 
velocity  of  2,721  foot-seconds.  Shell  not  home  by  4.4  inches, 
increased  velocity  27  foot-seconds.  Not  home  by  5.2  inches, 
increased  velocity  42  foot-seconds. 

S-iuch/45  Mark  VI  gun  gave  a  velocity  of  2,721  foot-seconds. 
Shell  not  home  by  0.6  inch  caused  loss  of  velocity  of  11  foot- 
seconds.  Shell  not  home  by  1  inch  caused  loss  of  velocity  of 
11  foot-seconds.  Shell  not  home  by  2  inches  caused  loss  of 
velocity  of  11  foot-seconds. 

5-iuch/Mark  VII  gun.  Shell  not  home  by  1  inch  caused  loss 
of  velocity  of  5  foot-seconds. 

12-inch/35  gun :  Shell  not  home  by  6  inches — loss  of  velocity 
40  foot-seconds. 

Foreign  reports  have  been  received  of  an  11-incli  gun.  Shell 
not  home  0.8  inch  caused  increased  velocity  of  27  foot-seconds. 
Sliell  not  hon\e  41.4  inches  caused  loss  of  velocity  of  295  foot- 
seconds  with  but  one-third  normal  pressure. 

Smoke  rings  are  not  believed  to  be  in  any  way  connected 
with  improper  shell  seating,  because  they  are  not  observed 
when    shells    are    fired    purposely  unseated  at  the    proving 


262 


GUNNERY  INSTRUCTIONS. 


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GUNNERY  INSTRUCTIONS. 


268 


ground,  and  because  they  occur  oftenest  and  best  with  blank 
charges  when  there  is  no  shell  at  all.  Greasing  the  muzzle 
of  a  saluting  gun  is  supposed  to  make  them. 


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254 


GUNNERY  INSTRUCTIONS. 


The  scale  of  "  rounds  fired  "  corresponding  to  different  seat- 
ings  can  be  found  from  slietcli  D'. 

456.  Density  of  loading. — In  general  as  the  density  of 
loading  is  increased  there  will  result  an  increase  in  pressure 


SKtTCH    D    1 


12"  45  CAL.  GUN    MARK   V. 
Shell  Seating  in  New  45  Cal  Gun 
Mark  V.  87.06' 


88  6  9  BO  9  1  9t  3^ 

SHELL   SEATING  IN   IHCHCS    FROM    BEAR    ENO  OF  TUBE 


(- 


60  C 


and  velocity.  With  the  standard  weight  of  charge  an  increase 
in  density  of  loading  could  be  obtained  on  board  ship  only  by 
having  the  shell  improperly  seated.    Some  guns  of  a  battery, 


GUNNERY  INSTRUCTIONS.  255 

however,  have  different  makes  of  breech  mechanism,  and  this 
may  cause  a  change  in  the  density  of  loading.  With  the  shell 
properly  seated  and  the  correct  weight  of  charge,  there  should 
be  no  variation  in  density  of  loading.  As  guns  erode,  how- 
ever, and  the  shell  seats  farther  down  the  bore,  there  results 
a  decrease  in  the  density  of  loading,  with  consequent  loss  of 
pressure  and  velocity. 

457.  Temperature  of  chamber,  bore  of  gun,  etc. — Nu- 
merous tests  have  been  made  to  determine  the  temperature  of 
the  gun  and  mushroom  head  after  repeated  firing. 

5-inch/51  gun  was  fired  20  times  as  rapidly  as  possible. 
Temperature  of  mushroom  after  last  shot  was  275°  F.  Tem- 
perature of  gun  before  firing  was  98.6°  F. 

10  shots  were  fired  in  a  5-inch/50  gun  In  1  minute  18  sec- 
onds. Temperature  of  mushroom  before  firing,  100°  F.,  after 
firing  196°  F.  Temperature  of  chase  of  gun  before  firing. 
101°  F.,  after  firing,  131°  F.    Temperature  at  muzzle,  158°  F. 

29  rounds  were  fired  from  a  5-inch/51  gun  in  3  minutes  45 
seconds.  Temperature  of  breech  face,  before  firing,  82°  F. ; 
temperature  of  breech  face,  after  firing,  290°  F. ;  temperature 
of  chase,  before  firing,  84°  F. ;  temperature  of  cha.se,  after  fir- 
ing, 162°  F. ;  temperature  of  muzzle,  after  firing,  304°  F. 

A  powder  charge  was  placed  in  the  chamber  immediately 
after  firing  the  29th  round.  The  charge  was  left  ia  contact 
with  hot  mushroom  for  four  minutes,  and  it  was  tlien  taken 
out  unharmed. 

3-inch/50  gun  was  fired  25  rounds.  Temperature  of  muzzle 
before  firing  was  72°  F.,  and  after  firing.  234°  F. 

.50  rounds  were  fired  from  the  same  gun.  Temperature  of 
muzzle  before  firing  was  95°  F.,  after  firing,  378°  F. 

A  foreign  3-inch/46  gun  was  fired  110  rounds  rapidly,  the 
maximum  temperature  reaching  394°  F. 

Most  automatic  rifles  reach  temperatures  of  700°  or  more, 
depending  upon  the  speed  and  length  of  firing.     It  is  found 


266 


GUNNERY  INSTRUCTIONS. 


that  cartridfies  phiced  in  these  guns,  after  rapid  tire,  will  fire, 
due  to  the  heat. 

So  far  as  concerns  the  ballistics  of  the  gun  it  is  evident 
that  the  heat  of  the  bore  will  increase  the  temperature  of 
the  powder  charge,  and  so  cause  an  Increase  in  velocitj'.  pro- 
vided the  charge  is  left  for  any  considerable  time  in  the  bore 
of  the  gun.  With  guns  fired  under  similar  conditions  this 
error,  however,  should  not  be  very  gx'eat. 

So  far  as  concerns  safety  it  would  appear  that  little  danger 
is  to  be  anticipated  in  the  firing  of  large-caliber  guns  under 
service  conditions. 

458.  First  and  subsequent  shots. — The  first  round  from  a 
gun  will  have  slightly  less  velocity  than  those  fired  imme- 
diately afterward.  After  the  second  round  no  increase  can 
be  detected,  and  it  was  only  by  persistent  averaging  for  a 
number  of  years  that  a  difference  between  the  first  two  was 
definitely  established.  It  is  about  25  f.  s.  for  the  3-inch,  di- 
minishing to  not  over  4J  f.  s.  for  12-inch,  for  which  gun  it 
therefore  means  about  25  yards  at  10,000.  The  effect  is 
greatest  in  winter  and  least  in  summer,  the  above  being  year- 
round  averages. 

NAVY  GUNS. 


Caliter. 

Num- 
ber of 
exam- 
ples. 

Num- 
ber 
show- 
ing; in- 
crease. 

Num- 
ber 
show- 
ing de- 
crease. 

Num- 
ber 
show- 
ing no 
change. 

Sums 
of  in- 
creases. 

Sums 
of  de- 
creases. 

Average 
differ- 
ence. 

13-inch 

3 

22 
13 
22 
14 
69 
39 
16 
32 

/3 
/13 
10 
15 
11 
43 
29 
13 
28 

0 
6 
3 
7 
1 
21 
8 

1 

0 
3 
0 
0 
2 
5 
2 
0 
2 

128 
223 
98 
287 
223 
975 
655 
319 
907 

0 
123 

7 

les 

2 

353 

118 

45 

55 

-t-42.7 

12-inch 

+  4.5 

lOmch 

-1-7.0 

8-inch 

+  5.4 

7-lnch 

-1-15.8 

6-inch 

-1-  9.0 

S-inch 

-1-13.8 

4-inch 

-H9.0 

3-inch 

-f-26.6 

230 

165 

51 

14 

3,845 

871 

-H2.9 

GUNNERY  INSTRUCTIONS. 
ARMY  GUNS. 


257 


12-inch 

15 
17 
7 
32 
25 
22 

9 

9 

6 

19 

17 

13 

6 

7 
1 

12 
8 
8 

0 

1 
0 
1 
0 

1 

253 
324 
146 
385 
306 
346 

62 

96 

120 

121 

99 

157 

-fl2.7 

lO-inch 

-f  7.5 

8-inch 

-*-  3.7 

6-inch    

+  8.3 

5-inch 

-f  8.3 

3-inch 

+  8.6 

113 

73 

42 

3 

1,760 

655 

+  9.4 

Leaving  out  of  account  the  13-incli.  of  which  only  tliree 
examples  occur,  it  will  be  seou  that  the  Indian  Head  records 
indicate  u  plus  difference  which  is  much  greater  for  small 
than  for  large  guns;  while  the  Sandy  Hook  records  indicate 
a  plus  difference  which  is  about  the  same  for  all  calibers. 
However  this  may  be,  the  evidence  seems  conclusive  that  the 
difference  is  not  svUficient  to  cdll  for  any  allowance,  or  indeed 
to  admit  of  any  allowance  being  made  for  it. 

Apart  from  the  effect  of  the  warming  round,  it  has  been 
suspected  that  it  makes  a  difference  whether  the  bore  is  dry  or 
oily.  According  to  an  English  writer,  the  fouling  from  one 
round  of  black  powder  caused  a  velocity  loss  of  25  f.  s.  (p. 
287  Brynek),  but  Russian  experi)ucnts  seemed  to  show  the 
reverse,  that  oil  in  the  bore  decreased  the  velocity  36  f.  s.  in 
a  light  gun.  The  effect  is  probably  much  less  in  12-inch  guns. 
At  Indian  Head  the  results  of  the  fir.st  round  fired  each  day 
from  a  12-inch,  using  always  the  same  powder,  were  com- 
pared. There  were  32  observations,  some  with  bore  oily  and 
others  with  it  dry,  and  in  contradiction  to  the  Russiou  experi- 
ments, the  oil  seemed  to  increase  the  velocity  11  f.  s.  Since 
this  is  less  than  many  of  the  variations,  the  results  are  not  to 
be  taken  as  showing  much  more  than  the  fact  that  the  differ- 
ence, if  there  is  one,  is  very  small. 

459.  Vibration  of  gun  due  to  droop  or  flexibility. — It  will 
be  found  that  all  guns  have  a  muzzle  -droop  which  can  be 
34776 — 18 17 


258  GUNNERY  INSTRUCTIONS. 

measured.  This  droop  is  greatest  in  the  longer  and  heavier 
guns,  and  the  amount  of  gun  droops  is  liuown  and  recorded. 
There  is  not  onlj-  a  droop,  but  a  sliglit  deflection  to  one  side 
in  almost  every  gun.  The  droop  is  partly  elastic,  for  when  a 
gun  is  placed  upside  down  it  also  droops  a  certain  amount. 
In  almost  all  cases,  however,  the  greatest  droop  occurs  when 
the  gun  is  in  the  normal  position.  This  droop  varies  some- 
what from  time  to  time  as  the  stresses  in  the  gun  are  varied 
by  firing. 

Note. — As  the  gun  is  fired,  forces  acting  in  the  bore  tend  to 
straighten  it.  and  the  various  forces  set  up  vibrations  which 
cause  the  muzzle  to  describe  a  curved  figure  to  the  right  and 
above  its  position  in  the  state  of  rest.  From  proviug-ground 
data  it  is  also  proved  that  practically  all  of  this  muzzle  move- 
ment take  place  after  the  projectile  has  left  the  bore  of  the 
gun  and  thus  has  no  effect  on  its  flight.  There  is  no  doubt 
that  flexibility  is  undesirable,  and  every  effort  is  made  to  re- 
duce it  as  much  as  practicable  in  designing  guns.  The  droop 
with  wire-wound  guns  is  about  twice  that  of  built-up  gnus. 
From  all  data  at  hand,  it  is  evident  that  the  only  error  caused 
by  droop  is  due  to  the  variation  in  droop  among  various  guns 
on  board  ship.  As  an  example  of  an  extreme  case  (the  Wyom- 
ing) the  variation  in  droop  (between  least  and  greatest) 
would  cause  a  difterencc  in  range  of  3-5  yards  at  10,000,  and 
these  are  the  worst  guns  in  service  for  droop. 

Droop  varies  with  life  of  gun,  apparently. 

Di'oop.     Inch. 

0  rounds 0.  G90 

18  rounds ,720 

20  rounds .725 

44  rounds .  600 

70    rounds .  G90 

Type  gun  has  greater  droop  than  other  12-inch  59-caliber 
guns.    Average  droop  of  12-inch  50-caliber  guns  is  0.435  inch. 


GUNNERY  INSTRUCTIONS.  269 

Jlaxiniuni  droop  is  about  0.510  inch.    Minimum  droop  is  about 
0.3G0  incli. 

460.  Variation  in  chamber  capacity. — There  is  a  sliglit 
variation  in  the  capacity  of  chambers  of  different  guns  of  a 
l)atter.v.  due  to  the  tolerances  in  manufactiu'e.  There  may  also 
be  slight  dillerences  in  the  chamber  capacity  due  to  modifica- 
tions that  have  been  made  in  the  design  of  the  forward  slopes 
of  the  powder  chamber.  Further  changes  in  the  capacity  may 
lie  occasioned  by  the  fitting  of  different  marks  of  breech 
mechanisms  to  the  same  type  of  gun.  All  these  changes  in 
capacity  produce  the  same  result.  If  the  capacity  of  the  cham- 
ber has  been  diminished  the  density  of  loading  is  increased, 
and  there  occurs  a  slight  increase  in  pressure  and  muzzle 
velocity.  With  an  increase  in  chamber  capacity  the  reverse 
occurs. 

461.  Ellipticity  of  bore. — If  the  bore  of  a  gun  is  elliptical 
a  consi(k>ral)le  error  may  be  caused. 

A  .5-inch  51-caliber  JNIark  VII  gun  did  not  true  up  at  the 
muzzle  during  manufacture  for  about  82°  of  the  circumfer- 
ence. The  diameter  of  this  part  of  the  muzzle  was  0.010  inch 
too  great,  running  to  0.003  inch  at  21  inches  from  the  muzzle. 
This  gun  was  hred  with  an  exactly  similar  standard  gun  at 
a  range  of  850  yards.  The  powder  and  all  other  variables 
were  alike  in  the  firings. 

The  standard  gun  was  tired  five  times  and  g;:ve  the  follow- 
ing errors  at  850  yards: 

Mean  vertical  error,  4.68  inches. 

Mean  lateral  error.  4.98  inches. 

The  elliptical  gun  was  fired  six  rounds  at  the  same  range 
and  gave  the  following  errors: 

Mean  vertical  error,  14.46  inches. 

Mean  lateral  error,  13.42  inches. 

Similar  results  were  olitained  in  the  test  of  a  3-inch  50- 
lii liber  gun.  the  muzzle  of  which  had  one  diametd'  O.OOS  inch 
too  great. 


260  GUNNERY  INSTRUCTIONS. 

As  guns  erode  it  is  found  tiiat  tlie  bores  are  worn  more  or 
less  elliptical.  In  general  it  will  be  found  that  tlie  greatest 
diameter  (facing  tlie  muzzle)  is  tlie  one  running  northwest 
and  southeast  tliis  diameter  for  riglit-handed  twist  being  in 
general  slightly  greater  than  the  vertical  diameter.  The  least 
diameter  is  the  horizontal  one. 

A  12-inch  45-caliber  Mark  V  gun,  after  tiring  183  rounds, 
showed  on  star  gauging  that  the  vertical  diameter  was  0.036 
inch  greater  than  the  horizontal  at  the  origin  of  rifling.  At 
the  muzzle  the  vertical  diameter  was  O.OIG  inch  greater  than 
the  horizontal. 

If  all  guns  of  a  battery  were  fired  the  same  number  of 
rounds  it  is  likely  that  little  error  would  be  introduced  by 
ellipticity,  as  all  guns  should  Avear  in  the  same  manner. 

462.  Projectile  leaving  bore  with  its  axis  inclined.— It  is 
likely  that  a  projectile  never  leaves  the  bore  of  a  gun  with  its 
axis  in  the  exact  line  of  the  bore  of  the  gun.  There  occurs 
an  initial  angular  deviation  which  may  be  in  any  direction. 
The  bourrelet  diameter  of  the  projectile  is  very  close  to  the 
diameter  of  the  bore  of  the  gun,  and  this  error  in  modern 
projectiles  should  be  small. 

Owing  to  the  fact  that  the  gun  starts  to  recoil  before  the 
projectile  gets  entirely  clear  of  the  bore,  there  may  be  an  addi- 
tional deviation  given  to  the  projectile  by  the  jump  or  the 
vibration  of  the  gun.  There  may  be  a  still  further  deviation 
occasioned  by  the  nonsymmetrical  escape  of  gas  as  the  pro- 
jectile leaves  the  muzzle.  It  is  impracticable  to  ascertain  the 
extent  of  these  errors,  howevei*. 

463.  Short  hang-fire. — No  variation  sihould  be  occasioned  by 
short  hangflres,  provided  the  pointer  maintains  continuous 
;iini.  If  the  hangfire  is  of  considerable  duration,  however, 
even  while  maintaining  continuous  aim,  there  may  be  an 
error  introduced  owing  to  the  fact  that  the  vertical  and  hori- 
zontal speed  of  displacement  of  a  gun  may  be  different  from 
that  existing  when  the  other  guns  of  the  battery  were  fired. 


GUNNERY  INSTRUCTIONS.  261 

464.  Erratic  flight  of  shell. — It  occnslonally  happens  that  a 
sliell  will  prove  erratic  in  flight.  In  the  case  of  new  guns 
this  defect  is  generall.v  to  be  found  in  the  banding  of  the 
projectile.  The  baud  uiaj-  be  either  stripped  from  the  pro- 
jectile or  sheared.  In  either  case  the  projectile  does  not  get 
correct  rotation  and  erratic  flight  or  even  tumbling  may  occur. 

In  the  case  of  eroded  guns  the  rotating  band  has  to  with- 
stand much  heavier  sti'esses.  and  there  comes  a  time  in  the 
life  of  the  gun  when  tlie  rotating  band  is  unable  successfully 
to  withstand  the  excess  stress.  The  rotating  band  is  gener- 
ally sheared  before  the  projectile  leaves  the  gun,  and  as  the 
projectile  gets  little  or  no  rotation,  tumlfling  and  erratic 
flight  will  occur.  Correct  flight  can  generally  be  restored  by 
using  rotating  bands  of  augumented  dimensions.  This  method 
is  not  practicable,  however,  for  any  extended  series  of  firings. 

465.  Muzzle  movement. — Recent  determinations  of  the 
muzzle  movement  during  recoil  made  by  tixcd  markers  scrib- 
ing on  horizontal  and  vertical  plates  secvu-ed  to  the  muzzle  of 
a  14-inch  gun  shows  that  the  total  vibration  is  over  an  inch. 
Nothing  happens  until  the  shell  is  well  clear.  The  droop  is 
§  to  i  inch  in  12-inch  30-ca liber  and  14-inch  in  45-calib(?r  guns, 
and  evidently,  from  the  above,  the  shell  nmst  leave  a  curved 
bore  taking  the  direction  of  the  final  tangent.  A  great  num- 
ber of  firings  at  plates  850  feet  distant  show  that  the  droop 
is  greater  than  that  calculated  from  the  trajectory  by  ap- 
proximately the  amount  needed  to  corroborate  the  above  rea- 
soning. The  droop  exists  when  the  projectiles  are  ranged, 
and  such  values  are  selected  for  the  coefficient  of  form  as  will 
make  range  tables  agree  with  actual  firings,  so  that  average 
natural  droop,  unless  variable,  is  eliminated.  When  guns  are 
langed  at  the  proving  ground,  the  quadrant  is  on  the  stiff 
l)art  of  the  bi-eech  ;  afloat  they  are  elevated  with  reference  to 
the  line  of  bore  sight,  which  is  a  sort  of  chord.  This  has  the 
effect  of  making  guns  afloat  shoot  just  a  little  further,  which 
effect,  however,  is,  if  anything,  desirable  in  making  up  for  the 
small  loss  in  range  that  the  wear  causes. 


262  GUNNERY  INSTRUCTIONS. 

466.  Heating  of  the  gun.— If  the  top  of  a  gun  is  heated 
more  than  the  underside,  due  to  exposure  to  sunlight,  the 
effect  of  unequal  expansion  is  to  make  the  gun  curve  down- 
wanl  a\\n.v  from  the  sun.  According  to  a  British  ordnance 
writer,  the  top  of  a  gun  is  3.6°  F.  warmer  in  summer  and  this 
may  even  reach  7.2°  F.  in  the  Tropics.  He  calculated  for 
British  12-inch  50-caliher  guns  that  the  droop  is  affected 
0.010  inch  per  degree  Fahrenheit.  As  the  total  temperature 
difference  in  summer  is  less  than  3.6°  F.,  it  could  not  be  more 
ihan  part  of  this  between  different  turrets  boresighting  at  the 
same  time,  and  droop  could  not  be  affected  more  than  a  few 
hundredths  of  an  inch  at  most. 

(From  article  in  Journal  of  United  States  Artillery  No.  107 

(p.  73),  1°  C.=47^  therefore  1°  F.=0.47'x|=0.26   minute,    and 

(p.  64),  0.092^^=2.35  minutes;  therefore  1°  F.  =0.26X^^=0.0102 
inch.) 

The  only  sights  that  temperature  changes  should  affect  are 
certain  of  the  ohler  ones  where  the  parallel  motion  mechanism 
is  partly  of  brass  and  partly  of  steel,  hut  the  calculated  error 
in  these  would  be  very  small. 

467.  Effect  of  change  of  temperature  on  straightness  of 
guns.— Experiments  have  been  recently  made  at  the  proving 
ground  to  obtain  data  related  to  the  effect  of  sunlight  on  the 
straightness  of  guns.  As  a  result  of  three  experiments,  it 
appears  that  consideriug  other  unavoidable  causes  for  varia- 
tion that  due  to  change  in  temperature  may  usually  be  ne- 
glected. For  instance,  in  the  case  of  a  12-inch  50-caliber  gun, 
pointed  south,  between  11.45  a.  m.  and  3.45  p.  m.,  with  a 
maximum  temperature  at  2  p.  m.  of  94°  F.,  the  change  in 
range  did  not  exceed  25  yards.  Tlie  maximum  variation 
through  the  24  hours  was  shown  by  the  ellipse,  5  minutes  high, 
and  9  minutes  wide  (see  experiment  No.  2),  which  corresponds 
to  125  yards'  range,  and  29  yards'  deflection,  at  10,000  yards. 
With  the  gun  tested,  there  was  but  little  deviation  before  7 


GUNNERY  INSTRUCTIONS. 


263 


a.  in.  The  deflection  maxima  toolv  place  at  10  a.  ni.,  and  4.30 
p.  m.,  and  the  droop  maximum  at  1.30  p.  m.  The  movement 
was  faster  in  the  evening  tlian  in  the  morning,  and  scarcely 
anything  after  8  p.  m.  It  is  not  kown  whether  or  not  the  heat 
from  firing  a  round  or  two  is  sufficient  to  cause  these  effects 
to  disappear. 

To  see  if  there  was  any  possibility  of  there  being  a  difference 
between  the  action  of  turret  guns,  where  the  breech  is  covered, 
and  guns  on  the  proving  ground  battery,  where  the  whole  gun 
is  exposed,  a  24-hour  droop  record  was  made  with  an  8-inch 
45-caliber  gun  uncovered,  and  again  with  a  tarpaulin  over  the 
breech.  There  was  no  practical  difference,  although  examin- 
ing the  records  critically,  the  one  with  the  breech  covered  was 
perhaps  very  slightly  larger.  The  gun  faced  north,  and  the 
record  was  much  smaller  than  for  12-inch,  the  dimension  being 
approximately  itj-inch  eacli  way  in  both  instances,  or  about 
one-third  as  large  as  for  the  12-inch. 

Briefly,  the  experiments  were  as  follows : 


Date. 

Gim. 

Maxi- 
mum 
tempera- 
ture. 

Gun 
pointed. 

Remarks. 

July     4, 1913 

June     28-39, 
1913. 

June    19,1913 

12-in?h.  50-caliber 

12-in3h,  50-caliber 

12-m:'h,  35-ca'iber 

'F. 
96 

94 

South... 
...do 

...do 

Selfrepording  device 
en  muzzle;  the 
p^Lnt  tra'^ed  an  el- 
lipse 0.35  in:h  wide 
by  0.25  in  :h  high. 

Te.es?fpe  rn  muzzle 
sighted  rn  s  reen 
316  feet  away. 
C'l  mputed  cur\  e  at 
muzz.e  was  irregu- 
lar, n't  cicsed,  and 
was  0.56  in:h  wide 
by0.3Sin'hhigh. 

Te.esjfpe  en  nnizz'e 
screen  327  feet 
away,  t  omputfd 
cur\e  irregular 
0.21  inch  wide  ty 
0.11  inch  high. 

264  GUNNERY  INSTRUCTIONS. 

468.  Sight  and  mounting: 

1.  Drift  error. 

2.  Sight  error  anfl  telescope  error. 

3.  Mount  error. 

4.  Jump. 

n.  Weather  variations. 

6.  Trunnions  not  horizontal. 

7.  Movement  of  mount  due  to  pitch  and  roll. 

5.  Motion  of  target. 

9.  Firing  through  powder  gases. 

469.  Drift. — The  drift  of  a  projectile  varies  with  tlie  initial 
velocity,  form  of  the  projectile,  finnl  twist  of  ritling.  angle  of 
elevation,  etc. 

Owing  to  tlie  fact  that  it  i.';  not  possible  to  give  the  exact 
values  to  the  weather  variations  tliat  obtain  during  a  firing, 
it  is  not  possible  to  give  more  than  an  approximate  value  for 
The  drift,  although  this  value  should  be  within  small  limits. 
It  is  known,  therefore,  that  the  drift  used  in  graduating  sights 
is  slightly  inaccurate,  but  it  is  within  as  clo.se  limits  as  are 
practicable  of  attainment.  The  drift  is  not  of  great  impor- 
tance so  long  as  all  guns  firing  are  of  the  same  caliber,  but 
when  different  calibers  are  fired  togetlier  variations  in  the 
drift  may  produce  lateral  dispersion  \inless  means  are  pro- 
vided for  bringing  tlie  calibers  together.  Fortunately,  in  high- 
power  guns  the  amount  of  drift  is  small  until  the  longer 
ranges  are  reached.  A  12-inch  2,700  foot-seconds  gun  has  a 
drift  of  but  13  yards  in  7,000  yards,  but  at  10,000  yards  this 
drift  becomes  32  yards.  At  the  longer  ranges,  therefore,  care 
should  be  taken  in  firing  different  calibers  of  guns  together  to 
see  that  lateral  dispersii>n  is  not  introduced  by  inaccuracy  of 
drift. 

470.  Sight  error  and  telescope  error. — There  is  an  error  in 
all  sights.  This  should  be  measured  in  dry  dock  and  be  re- 
corded in  minutes  of  arc.     In  guns  having  sights  attached  to 


GUNNERY  INSTRUCTIONS.  266 

slides  most  of  the  sight  error  is  caused  by  the  distoi  tioii  ur 
spring  of  tlie  parts  of  the  sights  or  by  lost  raotioii  or  improper 
installation. 

In  turi-et  guns  liaving  parallel  motion  sights  there  may  be 
an  additional  error  caused  by  the  arms  not  beina:  parallel  in 
the  different  positions  of  elevation  of  the  gun. 

It  is.  of  course,  highly  desirable  that  this  error  in  sights 
should  be  reduced  to  a  minimum,  as  accurate  long-range  fir- 
ing can  not  be  expecteil  without  accurate  sights. 

There  is  always  the  possibility  that  sights  may  be  im- 
[iidperly  graduated  either  for  range  or  deflection,  but  these 
graduations  are  made  with  extreme  care,  and  inaccuracies 
fi-oni  this  cause  are  hardly  possible.  If  desirable,  however, 
these  graduations  can  readily  be  veritied  when  the  ship  is  in 
dry  dock. 

Errors  in  telescopes  may  be  occasioned  by  parallax  or  by 
the  parts  of  the  telescope  being  deranged.  Owing  to  the 
strong  construction  of  telescopes,  however,  the  parts  are  not 
liable  to  much  derangement  and  parallax  can  readily  be 
avoided. 

471.  Mount  error. ^Tliere  is  a  limited  amount  of  tiexibility 
in  every  mount,  and  it  is  possible  that  the  gun  does  not  as- 
sume quite  the  same  direction  relative  to  the  .slide  each  time 
on  returning  to  battery. 

The  clearance  between  the  gun  and  the  slide  is  very  .small, 
however,  about  0.02  inch  on  the  diameter,  and  this  error  must 
be  insignificant.  All  guns  are  balanced,  usually  slightl.v 
breech  heavy,  so  that  the  bearing  conditions  should  be  the 
same  after  each  shot. 

472.  Jump. — Jump  is  the  increase  of  the  angle  of  departure 
resulting  from  angular  motion  of  the  gun  i)i  the  vertical  plane 
caused  by  firing.  The  angular  motion  comes  partly  from  the 
recoil  of  the  gun  (which  moves  to  the  rear,  various  distances 
up  to  about  2.7  inches,  according  to  the  calibei*,  before  the 


266  GUNNERY  INSTRUCTIONS. 

projectile  leaves  The  muzzle)  and  partly  from  elastic  yield- 
iug  of  the  mount  or  the  support  for  the  mount.  It  is  as- 
sumed that  the  support  for  the  mount  is  sufficiently  rigid 
and  that  any  jump  will  be  occasioned  by  the  yielding  of  the 
mount. 

The  conditions  at  the  proving  ground  and  those  on  board 
ship  are  quite  different.  At  the  proving  ground  the  supports 
for  the  mount  are  rigid,  and  any  jump  occurring  is  due  to 
the  yielding  of  the  mount.  It  is  generally  assumed,  too,  that 
the  jump  is  the  same  at  all  angles  of  elevation,  and  at  differ- 
ent angles  of  train,  though  it  is  evident  that  there  may  be 
more  or  less  variation  from  this,  depending  upon  various  con- 
siderations. 

The  value  of  the  jump,  whether  at  the  proving  ground  or  on 
board  ship,  is  very  small.  It  is  so  small,  in  fact,  that  it  is 
difficult  to  measure  it  at  the  proving  ground  and  impracticable 
of  measurement  on  board  shijj.  The  jump  at  the  proving 
ground  is,  in  general,  not  more  than  two  or  three  minutes  of 
arc.  It  is  likely  that  on  board  ship  this  value  is  not  greater 
than  five  minutes  of  arc.  In  a  12-inch,  2,700-foot-second  gun 
there  woidd  be  occasioned,  at  10,000  yards,  an  error  from  this 
cause  of  a))out  100  yards.  It  must  be  understood  that  this 
jump  would  not  produce  dispersion  unless  it  varied  from 
round  to  round,  and  varied  in  the  different  guns.  It  is 
evident,  therefore,  that  with  properly  designed  mounts,  which 
are  well  supported  on  board  ship,  the  error  due  to  jump  is 
not  of  great  consequence. 

In  addition  to  the  jump  in  the  vertical  plane,  it  is  likely 
that  there  may  be  some  small  lateral  errors  occasioned,  but 
these  may  be  neglected. 

473.  "Weather  conditions. — It  will  always  be  impossible 
accurately  to  state  the  effect  of  the  weather  on  firing.  It  is 
impossible  to  obtain  accurate  values  for  the  force  of  the  wind 
and  the  readings  of  the  barometer,  thermometer,  etc..  in  the 
different  parts  of  the  trajectory  of  projectiles,  and  the  state 


GUNNERY  INSTRUCTIONS.  267 

of  the  science  is  such  that  even,  were  the  cori-ect  values 
known,  their  effect  on  the  trajectory  could  only  be  approxi- 
mated. In  any  particular  firing  all  that  can  be  done  to 
niininiize  weather  variations  is  to  select  conditions  as  favor- 
able as  possible,  and  to  fire  rapidly  .several  shots,  taliing  the 
mean  result  of  the  firing. 

The  range  tables  and  books  on  exterior  ballistics  furnish  the 
best  information  available  of  the  effect  of  weather  variations 
on  tlie  trajectory.  It  is  evident,  however,  that  the  weather 
variations  may  produce  dispersion,  even  were  all  other  varia- 
tions eliminated. 

474.  Trunnions  not  horizoutal. — It  has  been  found  that 
.some  miiunt.-^  in  a  ship  are  jtlaced  with  the  axes  of  their 
ti'unnious  at  angles  with  one  another.  In  all  new  vessels  it 
h:  prescribed  that  the  axes  of  the  trunnions  shall  not  diverge 
more  than  1.3  minutes  of  arc  from  parallelism  to  a  common 
horizontal  plane.  Even  with  mounts  correctly  installed  with 
their  trunnion  axes  parallel  to  a  common  horizontal  plane  it 
may  happen  that  the  guns  are  fired  in  a  seaway  with  the 
trunnion  axes  considerably  inclined  to  the  horizontal.  The 
effect  of  this  is  to  introduce  a  lateral  error,  which  may  be 
right  or  left,  depending  upon  whether  the  ship  is  pitching  or 
'scending. 

If  the  guns  are  elevated  3°  from  the  horizontal  and  fired 
while  the  ship  is  pitching  3°  there  will  be  introduced  an  error 
of  sin.  3°Xsin.  3°  (tS?  by  t^^)  =1/361  of  the  range.  At 
7.000  yards  this  causes  a  lateral  error  of  19  yards.  At  longer 
ranges  (greater  elevations)  or  with  greater  pitches  this  error 
increases.  It  will  be  noted  that  if  the  ship  had  been  'scending 
the  salvo  wotild  have  struck  38  yards  from  the  first  impact. 

There  is  also  introduced  a  small  vertical  error,  but  this  is 
•vf  slight  importance. 

It  is  important  that  all  mounts  have  their  axes  parallel  to 
a  common  horizontal  plane  and  that  the  guns  be  fired  each 


268  GUNNERY  INSTRUCTIONS. 

liin<-    with    this    pl:me    relatively    at    the    same    angle    to    the 
horizontal. 

475.  Movement  of  mount  due  to  pitch  and  roll. — Should 
a  suii  be  fired  even  while  niaiiKaiiiiiijr  perfeet  ooniinuon.s  aim 
there  is  an  error  introduced  due  to  the  actual  vertical  dis- 
placement of  the  mount  caused  by  rolling  or  pitching.  The 
pitching  error  is  greatest  as  the  speed  of  the  vertical  displace- 
njent  due  to  pitch  is  considerably  greater  than  that  caused 
by  roll — probably  about  four  times  as  great.  It  is  also  evi- 
dent that  the  guns  in  the  ends  of  the  ship  are  affected  the 
most  by  the  pitch  and  that  the  guns  mounted  farthest  out- 
boa  i-d  are  affected  most  by  the  roll. 

In  this  connection  it  is  important  to  note  that  center-line 
mounting  of  guns  is  very  desirable  as  the  vertical  displace- 
ment of  these  mounts  is  inappreciable  for  small  rolls  of  2  or  3 
degrees  on  each  side  of  the  vertical.  The  error  due  to  a  roll 
of  2  or  3  degrees  would  be  not  more  than  a  foot  on  a  target 
at  7,000  yards.  For  a  3-degree  roll  the  8-inch  guns  mounted 
outboard  on  battleships  of  the  Connecticut  type  would  have  an 
error  on  a  7.000-yard  screen  of  about  6  feet,  provided  the  guns 
were  fired  in  the  middle  of  the  roll.  If  some  of  the  guns  were 
fired  in  the  middle  of  the  down  roll  and  others  in  the  middle 
of  the  up  roll,  the  impacts  would  be  separated  12  feet 
on  a  7,000-yard  screen.  This  error,  due  to  trunnion  displace- 
ment, is  really  the  component  of  the  trunnion  motion  acting 
on  the  motion  of  the  projectile,  and  of  course  the  error  in- 
creases with  the  time  of  llight. 

There  is  also  a  sliglit  lateral  error  introduced  by  the  lateral 
displacement  of  the  trunnion. 

476.  Motion  of  targ-et.— It  is  evident  that  the  vertical  mo- 
tion of  the  target  must  be  taken  into  account.  If  a  27-foot 
target,  at  a  range  of  7,000  yards,  is  fired  at  with  a  gun  having 
a  mean  vertical  error  at  that  range  of  ±10  feet,  the  percent- 
age of  hits  would  be  71.7.  If,  liowever,  the  target  has  a  verti- 
cal motion  of  5  feet  above  the  mean  and  5  feet  below  the  mean 


GUNNERY  INSTRUCTIONS. 


369 


position,  the  probability  of  hitting  is  reduced  to  67  per  cent. 
The  motion  of  rlit;  tarwi  lias  tlie  virtual  effect  of  increasing 
the  mean  error  of  the  gun  about  1  foot. 

With  greatfv  motion  of  the  target  the  probability  of  hitting 
is  fui-ther  reduced. 

477.  Firing  through  powder  gases. — Should  a  gun  tire 
through  smoke  or  gas  or  .it  a  time  when  the  strata  of  the  air 


«s 


Sketch  E. 

between  the  gun  and  taiget  are  of  unequal  and  varying  densi- 
ties, refraction  will  take  place  and  accurate  shooting  is  im- 
possible. Most  of  the  gas  which  is  discharged  from  the  gun 
is  heavier  than  air  and  therefore  causes  a  bending  of  the  rays 
of  liylit   toward    norma!.     Tf  the  gun  is  entirely  surrounded 


•~>a. 


Sketch  F- 


by   gas.   the  projectile   \vU\   go   high,   as   may   be   seen   from 
sketch  E. 

Target  will  be  seen  along  G-A  when  it  should  be  along  G-T. 
If,  hov.ever,  there  is  a  volume  of  air  on  each  side  of  the  re- 
fra(  ting  gas.  the  projectile  will  go  low,  as  shown  in  sketch  F. 


270  GUNNERY  INSTRUCTIONS. 

The  error  caused  by  this  refracting  gas  and  the  strata  of  air 
at  different  densities  is  very  considerable.  From  data  ob- 
tained at  1,600  yard  elementary  practice  where  tlie  gun  was 
ready  and  tlie  target  tired  at  as  soon  as  the  gas  thinned  so 
that  the  target  was  visible,  it  is  known  tliat  the  error  at  7,000 
yards,  caused  by  firing  under  similar  conditions,  would  be 
about  ±25  feet  on  the  vertical  screen.  This  error  is  so  serious 
that  it  nmst  be  avoided  wholly  in  order  to  permit  accurate 
shooting. 

478.  Personal  errors  of  pointer  and  sight  setters. — Tliere 
will  always  be  personal  errors  of  pointers,  some  of  wliom  will 
fire  when  eitlier  the  vertical  or  horizontal  wire  of  the  tele- 
scope is  not  on  the  target,  and  dispersion,  both  vertical  and 
lateral,  is  introduced.  Dispersion  will  also  be  introduced  if 
tlie  sight  setter,  due  either  to  personal  error  or  bad  trans- 
mission, sets  the  sights  incorrectly  in  i-ange  or  deflection.  If 
the  angular  error  of  pointing  is  known,  the  dispersion  due 
to  this  cause  can  readily  be  obtained  from  the  range  tables. 

Due  to  some  individuality  of  gun,  sight,  or  mounting  there 
may  be  a  definite  constant  error  for  a  particular  unit,  this 
i-.vvov  being  either  vertical  or  laterul.  Were  it  possible  to 
eliminate  all  olht-r  sdurces  of  error  this  constant  error  could 
be  detected  on  calibration;  but  it  is  evident  that  so  many 
errors  are  present  in  every  firing,  and  such  a  large  number 
of  rounds  would  have  to  be  fired  to  get  a  satisfactory  average, 
that  none  but  very  large  errors  could  be  found  by  calibration. 

There  is  no  reason  to  believe  that  the  constant  errors  of 
;:uns  and  mounts,  even  if  they  do  exist,  are  of  large  magni- 
tude, and  there  is  no  way  of  detecting  them  without  expend- 
ing large  quantities  of  ammunition  and  eliminating  all  other 
errors. 

It  is  practically  impossible  to  predict,  under  any  given  con- 
ditions, the  dispersion  that  will  occur  on  firing.  If  correct 
values  could  be  assigned  to  the  various  elements  producing 
dispersion,  the  probable  dispersion  would  be  obtained  by  tak- 


GUNNERY  INSTRUCTIONS.  271 

Ing  the  square  root  of  the  sum  of  the  squares  of  the  various 
elements.  It  is  not  practicable  to  make  more  than  an  ap- 
proximation to  tne  value  of  most  of  these  elements.  The 
only  practicable  way  of  obtaining  dispersion  data  is  to  cal- 
culate li-om  a  serieb  of  firings  the  dispersions  that  were  ob- 
tained. With  data  on  the  dispersions  of  a  number  of  guns, 
under  different  conditions  and  at  different  ranges,  it  is  possi- 
ble to  estimate  roughly  the  dispersions  that  will  be  obtained 
under  any  given  conditions. 


CHAPTER  20. 
REWARDS  AND  SCORES. 

479.  Battle  efficiency  pennant. — After  the  end  of  the  com- 
petition year  the  battle-efficiency  pennant  will  be  awarded  to 
the  vessels  of  the  battleship,  torpedo,  and  submarine  classes 
obtainini^-  the  highest  combined  final  merit  in  both  gunnery 
and  engineering  in  their  respective  classes.  The  weights  of 
the  various  forms  of  practice  with  guns  and  torpedoes  for  the 
year,  and  the  method  of  combining  gunnery  and  engineering, 
are  included  in  the  annual  rules. 

Before  combining  the  merits  of  gunnery  and  engineering 
oach  will  be  reduced  to  a  scale  of  100.000;  the  ship  attaining 
the  highest  merit  in  gunnei-y  or  engineering  in  the  class  will, 
for  purjvtses  of  combination,  be  given  100.000,  and  the  merit 
of  the  other  vessels  will  be  scaled  accordingly. 

It  is  probable  that  the  President  may  send  a  letter  of  com- 
mendation to  the  commanding  officer  of  the  pennant  winner 
of  the  battleship  class. 

Those  officei-s,  not  to  exceed  nine  in  number,  who,  by  their 
continued  efficient  work,  have  been  directly  responsible  for 
the  winning  of  the  battle-efficiency  pennant,  will  if  recom- 
mended by  the  commanding  officer,  have  a  copy  of  the  Presi- 
dent's letter  placed  on  file  with  their  records. 

480.  Gunnery  trophy. — By  direction  of  the  President  of  the 
United  .States  the  dej)artment  offers  trophies  for  excellence  in 
naval  gunnery  to  five  classes  of  vessels.  All  forms  of  practice 
for  the  year  are  given  weight  in  determining  the  final  merit 
for  the  various  classes.  The  trophies  are  awarded  at  the  end 
of  the  competition  year,  July  1. 

2-<2 


GUNNERY  INSTRUCTIONS.  273 

The  hattloship  class  inclinles  all  vessels  carrying  turrets. 

The  torpedo  class  includes  all  tui-pedo  boats  and  destroyers. 

The  submarine  class  includes  all  submarines. 

The  cruiser  class  includes  all  vessels  carrying  5-inch  or 
liirger  guns,  but  not  having  turrets. 

The  gunboat  class  includes  all  vessels,  except  torpedo  craft, 
carrying  no  guns  larger  than  4  inches  in  caliber. 

When  a  trophy  is  received  on  board  a  winning  vessel  there 
shall  be  appropriate  ceremonies. 

Should  a  vessel  holding  a  trophy  be  placed  out  of  com- 
n)ission  the  trophy  will  be  returned  to  the  department. 

Letters  commending  efficiency  in  gunnery  will  be  issued  to 
officers  deemed  worthy  of  such  distinction. 

481.  Battle  inefficiency. — The  time  has  arrived,  in  the  de- 
velopment of  combined  gunnery  and  engineering  efficiency. 
when  generally  speaking,  there  is  no  good  reason  why  great 
differences  in  the  combined  final  merits  for  tlie  year,  should 
exist  among  the  ships  of  the  same  type.  Among  ships  that 
have  performed  similar  duties,  when  one  ship  falls  markedly 
below  the  other  ships  of  the  same  type,  in  the  final  merit  for 
combined  gunnery  and  engineering  for  any  one  year,  there 
have  existed  inefficiencies  in  discipline,  organization,  training, 
or  routine,  to  cause  such  a  failure.  In  battle  no  amount  of 
explanation  can  compensate  for  a  failure  to  steam  or  a  failure 
t<    hit. 

THE   NAVY    E. 

482.  By  whom  worn. — In  order  to  distinguish  the  members 
of  turret,  gun.  and  torpedo  crews  that  do  exceptionally  good 
work,  the  members  of  these  crews  will  wear  a  white  E  on 
tlieir  blue  uniforms  and  a  blue  E  on  their  white  uniforms,  as 
specified  in  the  uniform  regulations. 

The  members  of  the  crew  who  are  authorized  to  wear  this 
mark  of  distinction   will   be  designated  by  the  department. 
34776—18 18 


274  GUNNERY  INSTRUCTIONS. 

their  names  -will  be  published  in  the  report  of  the  practice, 
and  they  will  wear  the  E  until  the  completion  of  the  next 
elementary  jiractice. 

In  determining  the  men  entitled  to  wear  the  distinctive 
mark  for  excellence  in  gunnery,  the  turret  and  handling- 
room  crew  will  be  taken  as  a  unit,  not  the  turret-gun  crews 
only. 

In  determining  the  men  entitled  to  wear  the  Navy  E  for 
excellence  in  torpedo  work,  the  torpedo  crews  in  the  same 
torpedo  room  on  battleships  and  armored  cruisers  will  be 
taken  as  the  unit,  and  on  torpedo  and  submarine  craft  the 
torpedo  crews  of  the  vessel  will  be  taken  as  the  unit. 

483.  How  supplied. — When  the  list  of  men  entitled  to  wear 
the  Navy  E  is  published,  sliips  on  which  they  are  serving  will 
be  supplied,  without  charge,  with  a  sufficient  number  of  both 
blue  and  white  E's  for  the  use  of  the  men  entitled  to  wear 
them.  If  a  regular  ship's  tailor  is  allowed  the  ship  he  will  be 
required  to  sew  these  marks  on  without  expense  to  the  men. 

484.  Limit  of  wearing. — The  commanding  officer  will  have 
all  the  Navy  E's  worn  by  members  of  the  crew  for  the  pre- 
ceeding  year  turned  in  and  destroyed  upon  the  completion  of 
the  elementary  practice. 

485.  Where  painted. — Winning  turrets,  guns,  torpedo  rooms, 
or  torpedo  tubes  shall  have  one  block  letter  E  not  more  than 
18  inches  high  painted  on  them  in  a  conspicuous  place.  This 
E  for  the  preceding  year  shall  be  removed  upon  the  com- 
pletion of  this  practice. 

PRIZES. 

486.  Appropriation  chargeable. — For  a  fiscal  jear  all 
prizes  for  Navy  crews  will  be  charged  to  the  appropriation 
"Gunnery  exercises,"  for  that  year,  all  prizes  for  the  Marine 
Corps  to  the  appropriation  "Pay,  Marine  Corps,"  for  that  year. 


GUNNERY  INSTRUCTIONS.  276 

487.  Value  of  prizes. — First,  second,  and  third  class  gun- 
nery prizes  will  be  issued  to  meritorious  crews,  and  the  prizes 
awarded  them  will  he  made  known  as  soon  as  possible  after 
the  completion  of  a  form  of  practice.  «The  present  value  of 
prizes  is  as  follows: 

First  prize  $20  per  man. 

Second  prize  $10  per  man. 

Third  prize  $5  per  man. 

Men  entitled  to  prizes.^Every  member  of  prize  crew,  in- 
cluding the  turret  mijtain.  gun  captain,  gunner's  mate,  and 
electrician,  whether  regular  oi-  supernumerary,  is  entitled  to 
a  prize,  unless  absent  through  fault  of  his  own. 

A  man  stationed  with  more  than  one  prize  crew  shall  re- 
ceive but  one  prize.  This  shall  be  the  highest  prize  awarded 
to  a  crew  with  which  he  is  stationed. 


CHAPTER  21. 
GUN  POINTERS  AND  TURRET  AND  GUN  CAPTAINS. 

488.  Gunnery  and  torpedo  recgrds. — The  instructions  for 
keeping  suunery  and  torpedo  records  .>^liall  be  closely  fol- 
lowed. 

GUN   POINTERS. 

489.  Pointers  that  fire. — No  pointer  shall  fire  at  elementary 
practice  unless  it  is  probable  that  he  will  be  on  board  at  the 
next  form  of  battle  practice. 

490.  Pay  of  gun  pointers. — See  Navy  Regulations,  1913, 
4442  (11)  and  4427  (19). 

491.  Assig-nment  of  gun  pointers  to  other  duty,  restric- 
tions against. — See  Naval  Instructions  2501  (2).     . 

492.  Optical  examination  of  gun  pointers. — See  Naval  In- 
structions, 2501  (3). 

493.  Pointers  must  serve  at  class  of  gun  at  which  they 
qualified. — Attention  is  invited  to  the  provision  of  the  execu- 
tive order  which  specifies  that  a  gun  pointer  shall  receive 
extra- pay  only  when  duly  qualified  and  regularly  detailed  by 
the  commanding  officer  and  serving  as  gun  pointer  at  a  gun 
of  the  class  at  which  he  qualified.  Thus,  if  a  secondary  gun 
pointer  or  an  intermediate  gun  pointer  is  stationed  as  a 
pointer  of  a  heavy  gun,  he  must  serve  in  such  capacity  with- 
out extra  pay  until  he  qualifies  at  the  heavy  gun  on  the  next 
form  of  practice  at  which  the  department  directs  that  point- 
ers will  be  qualified.     He   does  not,   however,   thereby   re- 

276 


GUNNERY  INSTRUCTIONS.  277 

linquish  his  qualification  as  intermediate  gun  pointer  or 
secondary  gun  pointer  by  reason  of  his  employment  at  a  heavy 
gun. 

The  above  does  not  apply  to  a  pointer  shifted  from  one  type 
of  gun  to  another  of  the  same  class. 

494.  Qualifications. — Gun  pointers  will  be  qualified  in  ac- 
cordance with  the  standard  determined  by  the  department  for 
this  practice.  The  commanding  officer  will  authorize  the  extra 
pay  allo^\•ed  to  such  men  as  are  qualified  regular  gun  pointers 
upon  receiving  the  notification  from  the  department. 

If  there  is  any  doubt  about  a  pointer's  allowed  score  the 
matter  will  be  subiuitted  at  once  to  the  Navy  Department  for 
decision,  with  recommendations  both  of  the  umpires  and  the 
ship's  ofl^cers,  and  that  pointer's  gunnery  record  will  not  bo 
filled  out  until  the  score  is  decided. 

495.  Recoinmendations  for  special  qualification  and 
change  in  a  pointer's  qualification. — All  changes  in  qualifica- 
tions of  pointers  shall  date  from  the  day  on  which  the  practice 
allowing  pointei'S  to  qualify  is  completed. 

In  order  to  prevent  manifest  injustice  to  pointers,  as,  for 
instance,  where  the  fire-control  party  is  at  fault  or  sights  are 
out  of  adjustment,  etc.,  umpires  and  commanding  officers, will 
report  all  such  cases,  giving  full  details,  so  that  the  depart- 
ment may  take  final  action  in  the  matter. 

496.  Qualified  pointers  not  stationed  at  guns. — When  a 
qualified  pointer  has  been  removed  from  his  position  as  pointer 
of  a  gun  by  order  of  the  commanding  officer,  and  is  present  on 
board  ship  during  the  practice  at  which  pointers  are  allowed 
to  qualify,  he  shall,  so  far  as  his  qualification  is  concerned, 
be  considered  as  having  fired  but  failed  to  qualify ;  but  this 
rule  shall  be  applied  only  in  case  the  pointer  was  removed  for 
a  cause  affecting  his  skill  as  a  pointer.  Pointers  of  interme- 
diate or  secondary  gims  that  have  received  training  and  have 
been  qualified  on  larger  vessels  may  not  be  fitted  for  such 
positions  on  small  craft  having  an   irregular,  quick  motion. 


278  GUNNERY  INSTRUCTIONS, 

There  should  be  no  hesitation  in  substituting  unqualified  can- 
didates for  qualified  pointers  in  cases  where  inaptitude  is  evi- 
dent. 

497.  Duration  of  qualification. — Pointers  are  I'equired  to 
qualify  at  each  practice  allowed  them  for  qualification.  A 
gun  pointer's  qualification  shall  last  until  the  next  opportu- 
nity for  qualification,  pi'ovided  this  occurs  within  two  years. 
If  no  opportunity  occurs  for  renewal,  his  qualification  shall 
expire  two  years  after  the  date  of  the  practice  at  which  the 
pointer  qualified. 

498.  Absence  of  pointer  through  his  own  fault. — A  pointer 
who  fails  to  fire  at  such  a  practice  through  a  cause  due  to  his 
own  fault — as,  for  example,  wlien  absent  without  leave — shall 
be  considered  as  having  fired,  but  failed  to  qualify,  and  his 
qualification  shall  be  void  after  the  date  of  completion  of  the 
practice  of  his  ship,  and  this  fact  shall  be  entered  on  his 
gunnery  record. 

499.  Absence  of  pointer  not  his  fault. — A  pointer  who  fails 
to  fire  at  a  practice  where  he  is  allowed  to  qualify  through 
no  fault  of  his  own — as.  for  instance,  where  a  pointer  is  duly 
excused  by  the  commanding  officer  (on  the  recommendation 
of  the  medical  officer)  and  does  not  fire  on  account  of  his 
physical  condition — shall  retain  his  qualification  until  two 
\ears  from  date  of  the  completion  of  the  practice  at  which 
he  last  qualified. 

500.  Extra  pointers. — When  a  regularly  qualified  pointer  is 
serving  on  board  a  ship  as  an  extra  pointer  and  has  no  op- 
portunity to  fire  for  qtuilification,  the  practice  shall  be  con- 
sidered, in  so  far  as  concerns  the  qualification  of  this  par- 
ticular pointer,  as  not  having  been  held ;  but,  as  elsewhere 
specified,  lie  shall  draw  his  extra  pay  only  when  actually  per- 
forming the  duties  of  gun  pointer. 

501.  Reenlistment  of  qualified  gun  pointer. — A  qualified 
gun  pointer  reenlisting  for  four  years  within  four  months 
from  the  date  of  his  discharge,  and  regularly  detailed  as  a 


GUNNERY  INSTRUCTIONS.  279 

pointer  at  a  gun  of  a  class  at  which  he  was  qualified  at  the 
time  of  his  discharge,  shall  be  entitled  to  tlie  corresponding 
extra  pay  during  the  unexpired  portion  f)f  Ihe  period  of  his 
qualification,  the  interval  of  time  between  the  date  of  his 
discharge  and  reenlistnient  to  be  included  in  this  period. 

502.  Employzneflt  of  qualified  pointers. — The  sole  object 
of  the  above  rules  is  to  create  a  class  of  gun  pointers  that  will 
be  as  nearly  permanent  as  possible.  Pointers  may  be  removed 
for  any  cause  affecting  the  efficiency  of  the  battery,  and  of 
this  the  connnandiug  officer  will  be  the  sole  .judge.  It  some- 
times happens. that  men  whose  scores  entitle  them  to  a  quali- 
ficatitin  as  gun  pointer  by  the  standards  fixed  by  the  depart- 
ment Miay  be  considered  by  their  officers  as  inferior  to  other 
men  available  for  the  position.  There  should  be  no  hesitancy 
ill  removing  such  a  man  when  the  efficiency  of  the  ship  will 
thereby  be  increased.  In  case  any  regularly  qualified  gun 
pointer  on  board  any  vessel  is  not  regularly  assigned  as  a 
pointer  of  a  gun  of  the  class  in  wliicli  he  has  qualified,  or  is 
removed  from  his  station  at  a  gun,  it  is  directed  that  the  fact 
be  at  once  reported  to  the  department.  If  the  fact  that  the 
man  is  not  employed  is  due  to  the  lack  of  a  vacancy  in  the 
class  of  gun  at  whicli  he  has  qualified,  the  commander  in  chief 
of  a  foreign  station  should  immediately  transfer  the  pointer 
to  anotlier  vessel  where  he  can  be  utilized,  and  so  state  in 
forvi'arding  the  letter. 

No  qualified  gun  pointer  stationed  at  a  gun  which  is  likely 
to  be  used  shall  be  landed  as  a  member  of  the  ship's  landing 
force. 

In  no  ease  shall  a  man's  conduct  or  any  other  consideration 
except  his  efficiency  as  a  pointer  be  permitted  to  affect  liis 
assignnient  as  a  gun  pointer  or  to  influence  his  removal  from 
that  station. 

503.  Turret  training'  pointers. — In  turrets  two  men  will 
be  detailed  as  training  pointers.     The  training  pointers    so 


280  GUNNERY  INSTRUCTIONS. 

detailed  will  act  as  sight  setters  for  each  other,  when  prac- 
ticable, and  the  first  and  second  pointers  (elevating)  will 
similarly  act  as  sight  setters  for  each  other.  Oi'diuarily  at 
elementary  practice  the  training  pointers  will  each  train  for 
cue  of  the  pointers  at  each  gun,  and  the  score  of  the  turret 
run  for  which  he  trains  will  be  taken  as  hft  score  in  consider- 
ing his  qualification  as  training  pointer.  In  case  on^  or  more 
of  the  pointers  for  whom  a  training  pointer  trains  makes  a 
low  score  that  is  manifestly  not  due  to  a  fault  on  the  part  of 
the  trainer,  a  special  report  of  the  circumstances  will  be  con- 
sidered by  the  department  in  awarding  the  training  pointer 
his  qualification. 

504.  Training  pointers  in  superposed  turrets. — FV^r  the 
purposes  of  elementary  practice  there  will  be  four  men  de- 
tailed as  training  pointers  in  each  superposed  turret.  Two 
of  these  training  pointers  will  train  for  the  eight-inch  guns 
and  the  others  for  the  twelve-inch,  as  in  double  turrets. 

505.  Training  pointers'  extra  pay. — Training  pointers  will 
receive  extra  pay  under  tlie  same  conditions  as  elevating 
pointei'S. 

TURRET  AND   GUN   CAPTAINS. 

506.  Assignment  of  turret  and  gun  captains  to  other 
duty,  restrictions  against. — See  Naval  Instructions.  1913, 
2501   (2). 

507.  Pay  of  gun  captains. — See  Navy  Regulations.  4427 
(20)   and  4442   (11). 

508.  Acting  appointments  as  tuiTet  captain,  first  class, 
and  chief  turret  captain. —  (1)  Acting  appointments  as  turret 
captains  to  fill  vacacies  in  the  complement  will  not  be  issued 
until  after  the  candidates  have  been  examined  and  recom- 
mended by  a  board  of  officers,  the  examinations  to  be  held  on 
board  the  ship  to  which  the  candidates  belong.     Permanent 


GUNNERY  INSTRUCTIONS.  281 

appointments  and  advancement  will  be  governed  by  the  same 
regulations  that  apply  to  other  petty  officers,  but  turret  cap- 
tains, first  class,  may  be  given  acting  appointments  as  chief 
turret  captains  only  after  passing  a  satisfactory  examination 
of  the  same  character  as  for  turret  captain,  first  class,  but  of 
a  moi-e  advanced  nature. 

(2)  Commanding  officers  will  select  candidates  that  appear 
to  possess  the  necessary  qualifications  from  intelligent  men 
of  mechanical  bent  and  good  promise  as  lending  men  and  will 
have  them  detailed  to  the  turrets  for  training  in  the  duties 
of  turret  captain  for  a  period  of  at  least  three  months.  After 
this  probationary  training  the  names  of  those  who  are  con- 
sidered desirable  candidates  will  be  sent  to  the  commander 
in  chief,  or  to  the  squadron  or  division  commander,  who  will 
order  their  examination  before  a  board  which  he  shall  ap- 
point, to  consist  of  n6t  less  than  three  officers,  the  majority 
of  the  board  to  be  turret  officers  detailed  from  a  ship  or  ships 
other  than  thc»se  on  board  which  the  candidates  are  serving. 
When  practicable  at  least  two  candidates,  but  preferably  more, 
will  be  nominated  for  each  vacancy  in  the  complement  in  order 
that  the  examination  may  be  competitive.  The  candidates 
who  pass  the  examination  will  be  eligible  for  acting  appoint- 
ments as  turret  captains,  first  class. 

(8)  In  no  case  will  an  acting  appointment  as  turi'et  cap- 
tain, first  class,  or  chief  turret  captain  be  given  unless  the 
examination  of  the  candidate  shows  that  he  is  not  only 
thoroughly  familiar  with  the  safety  precautions  to  be  ob- 
served in  the  service  of  the  guns  and  the  method  of  procedure 
in  the  case  of  a  failure  to  fire,  but  also  that  he  has  been  suf- 
ficiently drilled  to  make  instant  application  of  his  knowledge 
and  that  he  is  competent  to  take  full  charge  of  the  turret  at 
target  practice  or  in  action  In  the  absence  of  the  turret  officer. 

(4)  A  candidate  for  appointment  as  turret  captain  shall  be 
required    to    demonstrate    his    ability    before    the    board    by 


282  GUNNERY  INSTRUCTIONS. 

actually  drilling  turret  and  handling-room  crews,  preparing 
a  turret  for  target  practice  or  action,  operating  all  the  mech- 
anism, shifting  of  gas-check  pad,  going  through  the  procedure 
in  case  of  a  failure  to  tire,  and  in  other  ways  showing  his 
practical  ability  to  meet  the  various  conditions  and  require- 
ments in  the  care  and  handling  of  a  turret.  In  regard  to 
qualifications  that  can  not  be  practically  demonstrated  the 
candidate  will  be  closely  questioned  by  tlie  board  orally,  in 
order  that  the  readiness  of  his  knowledge  may  be  ascertained. 
(5)  The  following  headings  are  given  as  covering  the  sub- 
jects on  which  the  candidates  for  appointment  as  turret  cap- 
tains shall  be  examined  (in  the  report  of  examinations  these 
subjects  will  be  referred  to  by  letter  only)  : 

A.  Ability  to  station  and  drill  the  turret  and  handling-room 
crews. 

B.  Ability  to  prepare  the  turret  for  aftion. 

C.  Dexterity  in  the  operation  of  all  the  mechanism  of  the 
turret. 

D.  Familiarity  with  such  details  of  the  care  of  the  turret 
mechanism  as  come  under  the  cognizance  of  the  gunner's  mate 
of  the  turret. 

E.  A  thorough  knowledge  of  the  safety  precautions  to  be  ob- 
served in  the  service  of  the  guns  and  of  the  method  of  pro- 
cedure in  case  of  a  failure  to  fire. 

F.i  Ability  to  bore  sight  the  guns  and  adjust  the  telescopes. 

G.  Ability  to  shift  and  adjust  a  gas-check  pad  and  breech 
mechanism. 

H.  A  ready  knowledge  of  how  properly  to  direct  changes  to 
be  made  in  the  compensation  for  range  and  lateral  errors,  in 
order  to  bring  the  shots  on  the  target  again  after  they  have 
begun  to  fall  oft'. 

I.  A  thoi-ough  knowledge  of  the  firing  circuit,  with  ability 
to  detect  and  remedy  local  defects. 

J.  Ability  to  fill  the  recoil  cylinders  and  a  thorough  knowl- 
edge of  the  lock. 


GUNNERY  INSTRUCTIONS. 


283 


K.  A  knowledge  of  the  care  aud  preservation  of  tlie  shell 
rooms  and  magazines  and  of  the  various  powder  tests  and 
inspections. 

r..  Ability  to  adjust  knife-edges. 

M.  Knowledge  of  the  methods  of  receiving  ranges  and  bat- 
tle orders  aud  communicating  them  to  the  sight  setters  and 
pointers. 

N.  Ability  to  ring  and  adjust  Morris-tube,  dotter,  and  sub- 
caliber  apparatus  and  to  superintend  the  training  at  them. 

O.  A  practical  understanding  of  the  general  terms  used  in 
ordnance  and  gunnery  and  the  rules  for  conducting  target 
practice,  with  a  knowledge  of  the  danger  spaces  at  elementary 
and  battle  ranges. 

(6)  Reports  of  examination  will  be  in  the  following  foi-m. 
No  other  report  is  required.  These  reports  will  be  sent  by 
the  senior  member  of  the  board  to  the  commanding  officer  of 
tiie  ship  to  which  the  candidate  belongs.  The  report  will  then 
be  filed  with  the  man's  service  record,  unless  there  be  a 
vacancy  in  the  complement  and  he  be  given  an  acting  appoint- 
ment as  turret  captain,  first  class,  or  chief  turret  captain  to 
fill  this  vacancy,  in  which  case  it  will  be  forwarded  to  the 
Bureau  of  Navigation,  together  with  Form  No.  1-B. 

Report  of  examination. 

Candidate's  name Rate 

Attached  to  U.  S.  S. 

Date  of  examination ,  191__. 

(Scale  of  marks:  5,  excellent;  4,  very  good;  3,  good;  2,  fair;  1,  indifferent;  0,  bad.) 


Subject. 

Marks. 

Subject. 

Marks. 

Subject. 

Marks. 

A 

F 

K 

R 

G 

L 

P 

H        

M 

T) 

I 

N 

E 

J 

O 

284  GUNNERY  INSTEUCTIONS. 

We  certify  that  we  deem  the  candidate  °°to*be''^  ^"^'J' 
qualified  to  talj:e  charge  of  a  turret  at  target  practice  or  in 
action,  in  the  absence  of  the  turret  officer,  and  *^°^°°*  recom- 
mend him  for  acting  appointment  as  chief^\urre\"captafn. '^^^^^' 


(Signatures  of  members  of  the  board.) 


509.  Gun  captains. —  (1)  By  an  Executive  order  dated  July 
25,  1903,  enlisted  men  of  the  Navy,  and  extended  to  include 
Marines  by  Navy  Department's  Order  No.  223  of  September 
27,  1912,  who  are  regularly  detailed  by  the  commanding  officer 
of  a  vessel  as  gun  captains,  except  at  secondary  battery  guns, 
shall  receive,  in  addition  to  the  pay  of  their  respective  ratings, 
$5  per  month.  In  the  case  of  men  holding  certificates  of 
graduation  from  the  gun-captain  class  of  the  petty  officers' 
school,  this  $5  shall  include  the  $2  per  month  to  which  such 
certificate  entitles  them. 

(2)  No  man  shall  be  i-egularly  detailed  as  gun  captain  in 
the  above  sense  (that  is,  with  extra  pay)  unless  he  has  been 
examined  and  recommended  by  a  board  of  three  ordnance  or 
division  officers  (exclusive  of  his  own  division  officer,  if  prac- 
ticable) appointed  by  the  commanding  officer  to  determine  his 
fitness  for  the  position,  but  the  above  shall  not  be  construed 
as  preventing  the  detail  of  any  desirable  member  of  a  guu 
crew  as  acting  gun  captain,  though  such  detail  shall  carry 
with  it  no  extra  pay.  Such  details  are  necessary  in  order 
that,  prior  to  their  examination,  candidates  may  have  had 
actual  experience  in  their  duties  in  this  capacity. 

(3)  In  order  that  he  may  draw  his  extra  pay,  a  gun  cap 
tain  who  has  been  recommended  by  a  board,  as  above  de- 
scribed, must  be  regularly  detailed  as  captain  of  some  in- 
dividual gun  of  the  main  battery.     If,  however,  the  arrange- 


GTTNNERY  INSTRUCTIONS.  S8fi 

inent  of  the  ship's  battery  is  such  as  to  render  necessary  the 
detail  of  one  gun  captain  to  a  group  of  guns,  as  for  example, 
when  a  number  of  guns  are  more  or  less  isolated  and  require 
a  responsible  person  in  charge,  a  man  may  be  detailetl  as  gun 
captain  of  the  group  of  guns,  permitting  an  acting  gun  cap- 
tain to  relieve  him  at  his  own  gun.  In  no  case  will  the  num- 
ber of  men  on  board  who  draw  extra  pay  as  gun  captain 
exceed  tlic  number  of  guns  of  the  main  liattery  on  that  vessel. 
(4)  The  following  headings  are  given  as  covering  the  sub- 
jects on  w-hich  the  candidates  for  appointment  as  gun  cap- 
tains shall  be  examined  (in  the  report  of  examinations  these 
subjects  will  be  referred  to  by  letter  only)  : 

A.  Ability  to  station  and  drill  the  gun  crew. 

B.  Thorough  knowledge  of  the  safety  precautions  to  be  ob- 
served in  the  service  of  the  gun  and  of  the  method  of  pro- 
cedure in  case  of  a  failure  to  fire. 

C.  Ability  to  bore  sight  the  gun  and  adjust  the  telescope. 

D.  Familiarity  with  the  telescope  sights  of  the  gun,  in- 
cluding their  care,  the  precautions  to  be  observed  in  their 
use.  and  their  most  probable  derangements. 

E.  Ability  to  shift  and  adjust  the  gas-check  pad  and  breech 
mechanism. 

F.  A  practical  understanding  of  the  general  terms  used 
in  ordnance  and  gunnery. 

G.  A  thorough  familiarity  with  the  mount,  and  ability  to 
adjust  such  parts  as  require  adjusting  from  time  to  time. 

H.  A  ready  knowledge  of  how  properly  to  direct  the 
changes  to  be  made  in  the  range  and  lateral  compensation  in 
order  to  make  hits  again  after  shots  have  begun  to  fall  off 
the  target. 

I.  A  thorough  knowledge  of  the  firing  circuit,  with  ability 
to  detect  and  remedy  local  defects. 

.J.  Knowledge  of  the  metliod  of  receiving  ranges  and  battle 
orders. 


286 


GUNNERY  INSTRUCTIONS. 


K.  Ability  to  rig  and  adjust  Morris-tube,  dotter,  and  sub- 
caliber  apparatus,  and  superintend  the  training  at  them. 

(5)  Reports  of  examination  will  be  in  the  following  form. 
No  other  report  is  required.  These  reports  will  be  sent  by 
the  senior  member  of  tlie  board  to  the  commanding  officer  of 
the  ship  to  which  the  candidate  belongs.  The  report  will 
then  be  filed  with  the  man's  service  record. 


Report  of  examination. 

Candidate's  name,  Rate,  . 

Attached  to  U.  S.  S. 

Date  of  examination, 191- 


'Scale  of  marks:  5,  excellent;  4,  very  good;  3,  good;  2,  fair;  1,  indiflerent;  0,  bad.) 


Subject. 

Marks. 

Subject. 

Marks. 

Subject. 

Marks. 

A 

E 

I 

B 

F 

J 

C 

G 

K 

D 

H 

We  certify  that  we  deem  the  candidate  ^^^  qualified  for  the 
duties  of  a  gun  captain. 


(Signature  of  members  of  the  board.) 


INDEX. 


Article. 

Accuracy  of  fire^ 36 

pointing 37 

pointing  necessary 64 

torpedo  fire 190 

Adjustment  of  knife  edges 306  (c) 

Afternoon  work : 278 

Air,  density  of.  change  of  range  due  to 412   (3) 

Alignment  of  sights,  necessity  for  correctness  in_  301 

Ammunition   299  (d) 

crews,  drill  of 139 

supply 138 

supply,  broadside  guns 270 

Angle  fire,  torpedoes,  procedure  for 185 

Annoyances,  avoidance  of  petty 20 

Artificiality   143 

of  peace  exercises,  torpedo  vessels,  sub- 
marines    284 

Assembling  and  disassembling  torpedoes 180 

Assembling  men,  difficulties  of 280 

Battle,  diagram  for  spotters 371 

Battle  efficiency  pennant 479 

Battle  inefficiency 481 

Battle  signal  book 153 

Batten,  erecting -306  (b) 

Batten  method  of  checking  sights 306 

Bells  and  buzzers  fail 249  (I) 

Binoci:ar  vision 350 

Books  on  telephone,  recommended . 336 

287 


288  INDEX. 

Article. 

BOEE,   ELLIPTICITY  OF . 461 

BORESIGHT   TELESCOPE 318 

inverting  of 319 

BoRESiGHTiNG,  definition 311 

droop , 326 

errors  due  to  sights  not  being  in  hori- 
zontal plane  with  axis  of  boi-e 313 

errors  due  to  sights  not  being  in  ver- 
tical plane  with  axis  of  bore 314 

method  of 320 

necessary 312 

procedure  after  completion  of 322 

turret  guns,  procedure  in 323 

turret  trainer's  sight 316 

uniform  conditions  necessary 315 

BoEEsiGHTs,  adjustment  of 306  (g) 

preparation  of 317 

Breech  mechanism,  broadside  guns 267 

Broadside  battery,  general  hints  for  officers  of 260 

material 262 

organization  and  drill 261 

Broadside  gun,  salvo  fire 133 

Broadside  sights,  checking  of 303 

Broken  powder  bag 249  (e) 

Broken  rammer 249  (/) 

Bulletins,  torpedoes 171 

Burrs,  removing 91 

Buzzers  and  bells  fail 249  [1) 

Cable,  shell  hoist,  carries  away 249  (j) 

Calibration  and  fire  control,  problems  in 411-420 

Cards  for  recording  performance  of  gun  pointers 274 

Cartridge  cases,  primers,  etc 450-452 

Casualties ^ 28, 142 

turret 249 


INDEX.  289 

Article. 

Cease  firing 424 

Censvke.    reports  uiifl   coniniendation 17 

Chambek  capacity,  variation  in 460 

Change  of  range,  error  in  rate  of 410 

Charges,  duiniuy i 94 

reduced,  spotting  with 399 

(  'h.\u(;ei>  toki'Kuoes,-  prt'(;aulious 189 

Checking  sights  after  firing 325 

Check  telescope,  advantage  of 76 

conducting  drill  witli 81 

iiow  mounted 79 

with  uiechaniciil  target 77 

types 78 

<"hike  kike-contkol  officer 119 

Circuit  bijeakek  opens 249  (k) 

Cleaning  bill,  turret 232 

("leanliness  and  smartness,  necessitj'  for 12 

Clearing  of  vent 254 

Coils,  impedance,  telephone 833 

Collective  gunfire,  difficulties  of 151 

individual  ship 109 

several  ships,  training  for 145-153 

Commands,  giving  of 18 

Comsiendation,  censure,  and  reports 17 

Competition 13 

use  of  in  training 2a 

Concentration 149. 150 

(^'ondensers,  telephone 334 

Continuous  aim 59  (&) 

Coordination,  torpedo  training ^ 169 

r'REw,  selection  of,  for  broadside  guns 271 

suggestions  from 9 

Criticism  of  superiors 4 

34776—18 19 


290  INDEX. 

Article. 

Current  observations,  torpedo  firing 198 

Damage  to  torpedoes  result  of  inexperience 167 

Deck  lugs,  settling  of 306  (i) 

Deflection  corrections  for  observed  mean  error 412  (7) 

Deflection  due  to  wind 303 

initial,  method  of  obtaining 302 

initial,  thumb  rule  for  obtaining 304 

tables     305 

Density  uk  LoArnxo 450 

variations  in 432 

Destkovei;    actions    287 

gun   vu   286 

Details,  minor,  importance  of 21 

imiiortance   of 140 

Deterioration  of  torpedo  caused  by  salt  water 205 

Diagrams  and  signals,  torpedo  firing 204 

Direct  flight  method  of  spotting 354 

Directing,   importance  of  correct  torpedo 191 

torpedo   ■ 192 

Dispersion    114 

elements  of . 428 

mean,  method  of  estimating 374 

Distant  ob.ject  method  of  checking  sights 305 

Drv'isioN    practice    152 

Dotter.    advantages    of    _ 09 

delayed   action    71 

turret,  installation  of 220 

variety  of  design   70 

Double  and  single  kakkeled.  training  necessary  for 

tiring 132 

Drift   erkou    469 

Drill  at  Drill  gun 89 

at  spotting  board  and  procedure 392,393 

for  range-finder  party 342 


INDEX.  291 

Article. 

Drill  gun,  function  of 87 

gun,  use  of 88 

requirements 248 

shell 93 

Drills,  beginning 243 

Drills,    first 243 

service  conditions  in 29 

routine  of,  for  broadside  guns 272 

Droop  as  affecting  bore  sighting 326 

Dummy  charges 94 

Duties  of  turret  officer,  importance  of 211 

Elevating  gear,  turret 222 

Elupticitv  of  bore  of  guns 461 

Emery,  use  of 218 

Energy,  sources  of  for  telephones 335 

Erratic  depth  and  deflection,  torpedoes 183 

flight  of  shell 464 

Errors  of  gunfire 428-478 

necessity  for  elimination  of 41 

Example,  force  of 3 

Exit  pupil  of  spotting  glasses 348 

Eyes,  care  of  spotters' 353 

Failure  of  plug  to  close 249  {<j) 

FlELD^OF    SPOTTING   GLASSES 347 

Firing  connections,   subcaliber 85 

Fire  conthoi 111,  299(fif) 

broiidside  guns 269 

and  calibration,  problems  in 411-420 

cease   firing 424 

detriments  to 122 

facility  of 45 

elasticity    of 121 

operation  of  day   system   of 423 

station  bill 422 


292  INDEX. 

Article. 

FiBE  CONTROL,  station  bill,  general 421 

telephones 327-336 

FiKE,  in  turret  or  haudlinj^  room 249  {d) 

opening  of 116 

rapidity    of 42 

Firing  circuits,  broadside  guns 265 

Firing  connections 299   (c) 

panel,  turret  booth 223 

intermediate  guns ; 134 

interval 452 

signal,  necessity  for 80 

signals , 120 

turrets,  double-barreled 125, 128, 130, 131 

turrets,  double-barreled,  objections  to 127,  129 

Fixed  torpedo  range,  conditions  for 197 

Fragments  or  powder  bag 249  {in),  253 

Friction  disks,  broadside  guns 266 

Game  board  and  maneuvers 209 

Gas-e.tecting  system 249  (c),  268 

Glasses,  spotting,  power  of 346 

Gun  and    gun    mount 299  (e) 

ellipticity  of  bore  of 461 

heating  of.  variations  caused  by 466.467 

individual,  details  of  training 47-105 

laying,  necessity  for,  in  training 100 

method  of  operation 59  (c) 

movement  of  muzzle  of 465 

on  destroyer  286 

Gun  captains 506-509 

detail,  examination,  etc 509 

pay  of 507 

i-estrictions  as  to  duty 506 

selection  of  51 


INDEX.  293 

Article. 

Gun  crew.s,  devices  for  training 58 

selection  of 49,  234 

stationing  of 50 

Gun  drill,  joint  exercises  of  crew 96 

Gun  firk.  ability  to  sustain 137 

analysis  of  results 144 

collective,  historical  106 

errors  of 39 

excellence  in,  how  measured 35 

necessity  for  coordination   110 

prearranged  program  necessary 146 

program  prearranged,  necessity  for 146 

training  for  collective  on  individual  ships-  106 

Gun-mount  error 471 

Gun  pointers 488-504 

absence  own  fault 498 

ab.sence  not  fault 499 

assignment  of,  to  other  duty,  restric- 
tions  against    491 

duration  of  qualification 497 

employment  of 402 

expiration  of  enlistment 54 

extra   pointers   500 

group,  training  together 59  (e) 

optical  examination  of 492 

pay  of 490 

position  of.  at  gun 59  (a) 

•  liialified  and  not  stationed  at  gun 496 

qualification    : 494 

records 488 

reenlistment    501 

selection  of 52 

spare  sets   55 

special  qualification 495 


294  INDEX. 

Article. 

Gun  pointers  that  fire 489 

to   serve    at    class    of   gun    at    which 

qualified   493 

training  pointer's  extra  pay 505 

training  superposed  turret 504 

training  with  mechanical  targets 59 

turret  training 503 

Guns,  broadside,  individual  control  of 135 

errors  due  to  irregularities  of 453-467 

lining  up  of 263 

GxJNS.   proficiency   with 33 

running   in    of 264 

temperature  of 457 

variation  between  first  and  subsequent  shots—  458 

variations,  causing  erratic  flight  of  shell 464 

variation  in  chamber  capacity 460 

variation  of,  due  to  droop  or  flexibility 459 

in  rifling ^ 454 

Gunnery,  interference  with 147 

necessity   for  cooperation 46 

records  of  gun  pointers 488 

Gunnery   training,   analysis   of  principles 34 

final    objective 31 

final  stage  of 32 

for  collective  gun  fire 107 

Gunnery   trophies 480 

Gyros,  care  of,  on  submarines 296 

Gyro-setting  device,  outside,  care  of 186 

outside,    engagement   of 188 

outside,  procedure  for 185 

outside,   use   of 187- 

Handling  charged  torpedoes,  precautions  to  be  ob- 
served   189 

MEN      1-21 


INDEX.  29fi 

Article. 

Handling  men.  iuiportance   of 1 

methods   of ^ 7 

room,  crew  of 235 

torpedoes 181. 1S9 

Hang  fires 275 

Hang  fire,  variations  due  to 463 

Hints  for  officers  op  broadside  battery 260 

Hi.sTORY  OF  TO]{i'p:no 208 

Hitting,  chances  of 375 

rapidity   of 118 

Hygroscopic  condition  of  powder ^ 433 

Ignition   charge,  variation   in  weight  and   distrihu- 

tion  of 437 

Impedence  coils,  telephone 333 

Inaccurate  pointing,  result  of .,_  65 

Independent  control  of  guns 288 

fire • 125 

Individual  control  of  broadside  guns 135 

guns,  draining  for 289 

Initial  advantage,  importance  of 117 

deflection,  method  of  obtaining 362 

^^L0CITIES,  variation  in 440 

Inspections 15 

by  turret  officer 215 

Instructions,  torpedoes 170 

Interference  between  guns 123 

metliods  of  overcoming 124 

Intermediate  guns,  control  of 134 

Jump  error 472 

Junior  division  officers,  suggestions  for 259 

Knife  edges,  adjustment  of 306  (c) 

Lateral  displacement  of  splash,  diagram  of 367 

Leads,  electric,  turret 221 

Lessons  of  Russo-Japanese  War  regarding  torpedoes  285 


296  INDEX. 

Article. 

Leveling  guns 306  (d) 

Lights,  turret  and  handling  room 249  (b) 

Lining  up  of  guns 263 

List  of  division,  turret 228 

Loading    and     firing     torpedoes     submerged,     sub- 
marines   294 

Loading,  density  of 456 

drill,   broadside  guns 276 

in  connection  with  pointing  exercise- _  95,  96 

turret  guns 92 

exercises 244 

precision  of 90 

rapidity  of 43 

Loading,  uniformity  of 40 

variation    in   density   of  432 

Loads,    timing    245 

Log.  battei'y   214 

torpedo,  entries  in 178 

rough     177 

L().N(i  range  firing,  liints  for  spotter 405 

practice  spotting 404 

spotting  of  two  ctiliDers 406 

Lookouts,  fire  control  422 

Loss   OF  TORPEDOES 199 

Lubrication    219 

Machinery,  turret,  care  in  moving 210 

Maneuvers  and  game  board . 209 

^Iatertal.  broadside  battery 262 

torpedoes,  Icnowledge  of 166 

turret,    care    of 217 

Mean  dispersion,  method  of  estimating 374 

point  of  impact,  spotting 373 

Mechanical  devices,  advantage  of 60,  61 

disadvantage  of 02,  63 


INDEX. 


297 


Article. 

Mechanic.vl  target  drills  broadside  guu.s —  273 

necessity    for    accurate    adjust- 
ment      67 

necessity  for  sliill  with 66 

training    with 59 

Mechanism,  running  turkett 227 

Men,   comforts   of 19 

Importance  of  interesting,  in  work 8 

young,  particular  care  with 16 

Method  of  boee  sighting 320 

Morris  tube,  design  and  rig 73 

essential  features 75 

function    of 72 

turret   devices 74 

Motor  generator  for  telephone  circuits 835 

Mlsfires 275 

turret 249  (a) 

Muzzle,  movement  of  gun's ----- 465 

velocities,  variation  in 440 

Naval  gunnery,  general  principles  of 31-46 

Navy  "E" 482-485 

Night  drills 279 

target  practice,  spotting  for 403 

XoitENCLATT'RE.   torpedoes 172 

Note  book,  torpedo  officer 174 

Observations  for  current,  torpedo  firing 198 

Ob.servation  parties  for  torpedo  firing , 202 

Object  of  torpedo  training 165 

Officer,  first  attributes  of 5 

Officers,   self  training 2 

to  train  as  pointers 241 

Oil.  excessive,  in  .screw  box 252 


298  INDEX. 

Article. 

Opportunities,  seizing  of 10 

for    torpedo   training,    talse   full    ad- 
vantage of 168 

Optical  characteeistics  of  spotting  glasses,  laws 

governing 349 

Ordnance  pamphlets   47  210 

instructions 48 

Organization  and  drill,  broadside  battery 261 

of  range  finder  parties 340 

submarines 291 

Pamphlets,  torpedoes 171 

Parallax,  spotting  affected  by 366 

Parallelism  of  guns 309 

Parties  for  observation  in  torpedo  firing 202 

Pay  of  gun  pointers 49O 

Peace  exercises,  artificiality  of 284 

Performances,  investigation  of  unsatisfactory 30 

unsatisfactory 105 

Personnel  of  grot-p  control  parties  for  torpedo  de- 
fense, fire  control 426 

Petty  officers,  general H 

Pitch  and  roll,  movement  of  gun  mount  cased  by 475 

Plug,  failure  to  close 249(g) 

sticks 249(71) 

Point  of  aim : 99 

correction  for 412  (5) 

Point  of  impact II5 

Pointers,  cards  of,  for  recording  performance  of 274 

detail    of    drills,   mechanical    target,    for 

broadside  guns 273 

development  of 238 

method  of  scoring  for 240 

officers  to  train  as 241 

preliminary  instruction 237 


INDEX.  299 

Article. 

Pointers,  selection  of 239 

jind  sight  setters,  personal  error  of 478 

station  of 236 

trained  in  larger  vessels,  proficiency  of,  on 

destroyers 290 

I'oiNTiNG,  rapidity  of 44 

Poor  scores,  causes  of 300 

Possibilities  of  actual  service 206 

Powder  bag,  broken 249(e) 

fragments  of 249  (m),273 

wrong  end  first 249 (i) 

Powder,  blending  of,  imperfect 435 

charge,  left  in  gun 251 

variation  in  form  of 438 

variation  in  temperature  of 431 

variation  in  weight  of 430 

errors 429-442 

gases,  errors  when  firing  through 477 

hygroscopic  condition  of 433 

ignition  charge,  variation  in  weight  and  dis- 
tribution of 437 

passing _ 247 

temperature  of,  change  of  range  due  to 412   (4) 

unconsumed 442 

unsuitability  of,  for  a  gun 439 

variation  in  age  of 434 

variation  in  weight  of 430 

Practice,  day  individual ' 141 

Precautions  before  firing  torpedoes 182 

to  be  observed  in  handling  charged  tor- 
pedoes     : 189 

preparation  lor  target  practice 298 

Pressure  on  sight  mechanism  forbidden 324 

Primers    451 


300  INDEX. 

Article 

Priming 246 

Prizes  486,487 

I'FtocKDur.E  before  and  during  battle  practice 282 

during  target   practice 281 

Pkobability   of   hitting 375 

Pito.TECTTLEs,    ei'rors 443-^49 

following  in  flight 35') 

form  of,  importance  of 447 

leaving  bore  with  its  axis  inclined 46"J 

not  concentric  with  bore  of  guns 449 

position  of  center  of  gravity 448 

seating  of 455 

variation  in  diameter  of  bourrelet 445 

variation  in  rotating  bands 446 

variations  in  weight 444 

Protection  afforded  by  well-directed  fire 108 

Proving  torpedo  practice 196 

under    way 200 

without  a   regular  range 201 

Publications,  torpedoes 171 

Racks,  shell,  refilling  of 257 

Rammer  broken 249  (/) 

Range  corrections,  summary  of 412  (6) 

Range  finders 337-342 

Bausch  and  Lomb,  operation  of 339 

care   of 338 

drill  routine  recommended 342 

general 337 

Ordnance  pamphlet 341 

operation  of 341 

organization  of  parties 340 

Range,  fixed  torpedo,  conditions  for 197 

Ranges,  necessity  for  accuracy 98 


INDEX.  301 

Article. 

Range,  repair  party,  targets,  etc 299  (b) 

sight  bar 113 

strips,  setting  of 306  (e) 

Ranging  shots 409 

Rapidity  of  fire 42 

hitting .__  118 

loading , 43 

pointing 44 

Rapidity  of  fike,  torpedoes 184 

Rate  of  change  of  range,  error  in 410 

Ray  filters ;_  255 

Recording  performances  of  gun  pointers 274 

Records,  gunnerj'  and  torpedo 488 

of  torpedoes,   importance  of 175 

Recovery  of  torpedoes 203 

Reduced  charges 441 

spotting  with : 399 

Removal  of  tompion 2.56 

Reports,  commendations,  and  censure 17 

Requirements  for  torpedo  directing 193 

Responsibility,  turret  officer 212 

Results  of  sight  alignment,  checlcing  of 306  (/) 

Results,  torpedoes,  responsibility  for 179 

Rewards  and  scores :. 479_4S7 

Rifling  of  guns,  A'ariations  in 454 

Roller   path,    turret- 1 220 

Routine  of  drills,  for  broadside  guns 272 

Routines,    torpedoes 173 

Running   in   of  guns 264 

S.\fety  of  crew,  turret 225 

Safety  precautions,  misfires  and  liangfires 275 

Salvo    spotting 372 

Scales,  sight,  adjustment  of 321 


802  INDEX. 

Article. 

Scores    and    rewards 479-487 

at  drill 82 

poor,  causes  of 300 

Scoring,  method  of,  for  pointers 240 

Screw  box,  excessive  oil  in 252 

Seating  of  projectiles 250,  455 

Selecting  of  crew  for  broadside  guns 271 

Service,   actual,   possibilities  of 206 

Shell,  erratic  flight  of 464 

racks,  refilling  of , 257 

seating  of 250 

variation  in  weight  of,  change  of  range  caused 

by    412   (2) 

Shots,    bunching  of 56 

variation  between  successive 458 

Sights    299  (/) 

alignment  of,  necessity  for  correctness  of 301 

causes  of  error  in 302 

Sights  and  mounting,  errors  in 468 

Sight  alignment,  adjustment  to  be  made  by  yard 

force    310 

checking  after  firing 325 

checking  of,  by  batten  method 306 

checking  of,  by  distant  object  method 305 

checking  of  broadside 303 

error  and  telescoiie  error .       470 

Sight  lag  in  range  of • 307 

scales,    adjustment   of . 321 

tabulation  of  results  in  checking 308 

turret,   checking 304 

Sight-bar   range 118 

range  finder  and  spotting  both  em- 
ployed    344 

regulation    of 344 


INDEX.  303 

Article. 

Sight  setters,  .selection  of 53 

and  pointers,  personal  errors  of 47S 

Sight  setting 38,59  (d) 

broadside  guns 277 

necessity  for,  in  training 100 

S1GXAL.S  and  diagrams,  torpedo  firing 204 

firing    120 

turi-et ^ 224 

Smauxness  and  cleanliness,  necessity  for 12 

Specification.s  and  telephone  PAMPHLfrrs 336 

Sj'i.a.sh  uiAGKAM,  exphuiation  of,  for  short  range 368 

for  long  range 369 

Splash,  lateral,  displacement  of.  diagram  of 367 

Splash  ok  vertical  method  of  spotting 359 

Spot  points  on  battens 306  (h) 

.Spotter 136 

Spotter's  battle  diagram 371 

Spotters,  care  of  eyes 353 

e.s.sentials  in  training  of '  .384 

hints  for,  on  long-range  firing 405 

importance  of 345 

officer  in  charge  of  training  of 383 

selection    of 381,382 

should  be  given  opportunity  to  observe  fir- 
ing of  ships  other  than  their  own 401 

training  devices  for ,385 

training  for  battle 370 

training  for  long  range 388,389 

training  for  night  practice 387 

training,  preliminary 386 

Spotting  343-410 

calculations  and  diagi-ams 356 

calculations    of    data    for    "  shorts "    and 

"overs"  360 


304  INDEX. 

Article. 

Spotting  diagram,  example  of,  for  day  practice 3 

diagram,  example  of,  for  uigbt  practice 358 

elementary  practice,  points  to  observe 402 

direct    fiigbt    method 354 

long  range  practice 404 

method   of   halving 380 

methods  of  shorts 372 

method  of  shorts,  principles  of 379 

method  of  shorts,  advantage  of 378 

necessity  for 343 

night  target  practice 403 

practice  with  great  gmis 400 

with  reduced  charges 399 

salvos 372 

subcaliber  practice 398 

Spotting  and  fike  controi..  notes  on 112 

Spotting  noAKn.  ])roblems 394 

dimensions  of 390,391 

drill  at.  and  procedure 392.  393 

Spotting  glasses,  binnocular  vision,  advantage  of 350 

exit  puiiil  of 348 

field  of 347 

mounting  of 352 

optical  characteristics  of 349 

power  of 346 

stereoscopic  effect 351 

Spotting  kange,  details  of 395.396 

drill  nil,  and  examples 397 

Spottt?jg  t.\ht.e.  inetliod  of  shorts,  analysis  of 377 

Spotting  taho:.  method  of  shorts 376 

of  "shorts"  and  "overs" 361 

vertical  or  splash  method 359 

Spots,  estimation  of  the  amounts  of . 373 

Stereoscopic  effect  of  spotting  glasses 351 


INDEX.  306 

Artirlf. 

Sticking  of  plug 249  (h) 

Storage  battery  for  telephone  cibcuits 335 

Station  bills,  fire  control 421-427 

Stations,  permanence  in 27 

SuBCALiBER,  (lata,  table 86 

practice,    spotting 398 

practice,  value  of 83 

rifles,  adjustment  of 84 

Submarines,  care  of  gj-ros 296 

care  of  torpedoes 295 

organization 291 

recovering   torpedoes 293 

submerged,  loading  and  firing  torpedoes  294 

tests  of  torpedoes 297 

torpedo   firing 292 

Suggestions  junior  division  officers 259 

miscellaneous,  for  target  practice 299  (a) 

target  practice 299 

Talks  on  drills,  etc 258 

Target,  errors  due  to  motion  of _' 476 

gravity  of  mistaking 101 

Target  practice,  elementary 103 

elementary,  development  of 104 

function  of,  in  system  of  training.  102 

long  range,   spotting  for 404 

night,  spotting  for 403 

preparations  for 298 

procedure 281,  282 

suggestions   for 299 

Team  work,  torpedo  training 169 

Teij;phones,    comparison    between    fire    control    and 

ship's  service 327 

fire  control 327-33ff 

34776—18 20 


306  INDEX. 

Article. 

Telephones,   fire  control,  care  and  operation 332 

transmitters,   conditions  governing  use 

of  different  types 330 

transmitters,   new   type 331 

types  for  fire  control : 328 

types  in  use 329 

Telescope,  adjusting  of 306   (/) 

boresight    318 

error  and  sight  error 470 

Test   torpedo   practice 195 

Tests  of  toei^edoes,  submarines 297 

Timing  loads 245 

ToMPioN,  removal  of 256 

'Torpedoes,   care  of,   submarines 295 

Torj'-EUO    DElvENSE 154-164 

artificiality  of  practices 162 

concealment    163 

different  ships,  different  ways 161 

fire-control  operation  of  system 427 

fire  control,  personnel  of 426 

example      during      Russo-Japanese 

War    - 155-159 

necessity  for  definite  program 164 

problem   154 

rapidity  and  volume  of  fire 160 

searchlights    163 

Torpedo,   deterioration 205 

directing 192 

directing,    importance   of   correct 191 

directing  requirements  for 193 

firing,  fire  control  of 425 

submarines   292 


INDEX.  307 

Article. 

ToBPEDOEs,  knowledge  of 166 

lessons  of  Russo-Japanese  War 285 

loss   of 199 

recovery   of 203 

recovery  of  by  submarines 293 

ToEPEDO  PRACTICE,  klnds  of 194 

proving 196 

test    195 

Torpedo  records 488 

record    books 176 

Trainees,    turret 57 

Training,  essentials  of,  torpedo  vessels,  submarines 283 

final  purpose  of 26 

for  collective  gunfire  on  individual  ship 106 

for  individual  control  of  guns 289 

gear,  lost  motion  in 97 

general  principles  of 22-30 

more  important  than  material 23 

progressive  with  dotter  and  Morris  tube 68 

system  of 24 

Transmitters,  telephone,  conditions  governing  use  of 

different   types 330 

telephone,  new  type 331 

Trial  shots 407,  408 

Trunnions  not  horizontal,  error  due  to 474 

Turret  captain 230 

acting  appointment 508 

examination    505,  508 

restriction  as  to  duty 506 

Turret  and  gun  captains 506-509 

Turret  force,  duties  of 231 

living  quarters  for ' 233 

selection  of 229 


308  INDEX. 

Article. 

Turret  guns,  bore  sighting,  procedure  in 232 

loading   drill 92 

Turret  officer^  methods  to  he  followed 213 

Turret  officer,  importance  of  duties 211 

responsibility  of 212 

Turret   sights,   checking 304 

Two-cALiBER  SHIPS,  Spotting 406 

Understanding  individuals,  importance  of 6 

Vent,   clearing  of 254 

Vertical  or  splash  method  of  spotting 359 

War,  training  for 22 

Weapon,  importance  of  torpedo  as 207 

Weather  conditions,  error  due  to 473 

Wind,  component  in  line  of  fire 412(1) 

deflection  caused  by 363 

Wrong  target,  firing  at 148 


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